TY - JOUR A1 - Schartel, Bernhard A1 - Weiß, André A1 - Sturm, Heinz A1 - Kleemeier, M. A1 - Hartwig, A. A1 - Vogt, C. A1 - Fischer, R.X. T1 - Layered silicate epoxy nanocomposites: formation of the inorganic-carbonaceous fire protection layer N2 - The layered silicate (LS) modification and processing parameters applied control the morphology of the LS/polymer composites. Here, increasing the surface area of the LS particles by using alternative drying processes increases dispersion towards a more typical nanocomposite morphology, which is a basic requirement for promising flame retardancy. Nevertheless, the morphology at room temperature does not act itself with respect to flame retardancy, but serves as a prerequisite for the formation of an efficient surface protection layer during pyrolysis. The formation of this residue layer was addressed experimentally for the actual pyrolysis region of a burning nanocomposite and thus our results are valid without any assumptions or compromises on the time period, dimension, surrounding atmosphere or temperature. The formation of the inorganic-carbonaceous residue is influenced by bubbling, migration, reorientation, agglomeration, ablation, and perhaps also delamination induced thermally and by decomposition, whereas true sintering of the inorganic particles was ruled out as an important mechanism. Multiple, quite different mechanisms are relevant during the formation of the residue, and the importance of each mechanism probably differs from one nanocomposite system to another. The main fire protection effect of the surface layer in polymer nanocomposites based on non-charring or nearly non-charring polymers is the increase in surface temperature, resulting in a substantial increase in reradiated heat flux (heat shielding). KW - Nanocomposite KW - Fire retardancy KW - Epoxy resin KW - Fire behavior KW - Flammability PY - 2011 DO - https://doi.org/10.1002/pat.1644 SN - 1042-7147 SN - 1099-1581 VL - 22 IS - 12 SP - 1581 EP - 1592 PB - John Wiley & Sons, Ltd. CY - Chichester AN - OPUS4-24916 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kovalev, Alexander A1 - Sturm, Heinz T1 - Observation of nanoscale hot-spot generation on a 2, 4, 6-trinitrophenol (TNP) single crystal N2 - An energetic material (EM) creates a local thermal point when it accepts energy and the EM will explode due to thermal decomposition when the hot-spot temperature reaches the explosive temperature. The initial stage of the hot-spot formation on 2, 4, 6-trinitrophenol (TNP) single crystal has been observed at the nanometer scale using atomic force microscopy (AFM). The hot-spot generation has been directly initiated by means of an AFM tip. The phenomenon is accompanied by producing agglomerated spherical-like nanoparticles due to a low-temperature decomposition of TNP. It has been observed that the agglomerated particles are produced outside of the stimulated region. The observed decomposition process at the nanoscale doesn't lead to a self-sustaining shock as detonation or explosion. The results are of interest in relation to explore the origin of deformation-induced chemical decomposition or detonation of EM. KW - Energetic material KW - Hot-spot KW - Atomic force microscopy KW - Scratching KW - Dynamic ploughing lithography KW - Nanomanipulation KW - 2, 4, 6-trinitrophenol PY - 2011 DO - https://doi.org/10.1016/j.susc.2011.06.012 SN - 0039-6028 VL - 605 IS - 17-18 SP - 1747 EP - 1753 PB - Elsevier CY - Amsterdam AN - OPUS4-24367 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Solomun, Tihomir A1 - Schimanski, A. A1 - Sturm, Heinz A1 - Illenberger, E. T1 - Efficient Formation of Difluoramino Functionalities by Direct Fluorination of Polyamides N2 - Efficient formation of difluoramino (NF2) groups within the polymer matrix upon exposure of polyamides (PA6 and PA12) to elemental fluorine is reported. The reaction was assessed on bulk and thin-film samples by means of RA-FTIR (reflection–absorption FTIR), XPS (X-ray photoelectron spectroscopy), and NMR (nuclear magnetic resonance) techniques. Direct fluorination causes cleavage of the amide C–N bond and concomitant formation of the NF2 chain-end functionalities as evident from an exceptionally large shift (+5 eV) of the N 1s binding energy and an increase of the v(CO) frequency by about 80 cm-1. The structural model is supported by the 19F NMR spectra of volatile reaction products that clearly reveal the presence of the NF2 group. PY - 2005 DO - https://doi.org/10.1021/ma050067c SN - 0024-9297 SN - 1520-5835 VL - 38 IS - 10 SP - 4231 EP - 4236 PB - American Chemical Society CY - Washington, DC AN - OPUS4-22624 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Messung elektrischer Eigenschaften in der Rasterkraftmikroskopie: der Aufladungskontrast auf nichtleitenden Oberflächen T2 - Tagung "Raster-Sonden-Mikroskopien und organische Materialien IV" CY - Munich, Germany DA - 1995-10-11 PY - 1995 AN - OPUS4-6389 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Weba, Luciana A1 - Silbernagl, Dorothee A1 - Mota Gassó, Berta A1 - Höhne, Patrick A1 - Sturm, Heinz A1 - Pauli, Jutta A1 - Resch-Genger, Ute A1 - Steinborn, Gabriele ED - Khayat, Kamal Henry T1 - Influences of nano effects on the flow phenomena of self-compacting concrete N2 - Chemical admixtures like superplasticisers or stabilising agents are of ever increasing importance for modern concrete technology. They liberate the workability of concrete from its dependency on water content, and thus, open the gate towards innovative and future oriented concrete technologies such as selfcompacting concrete. Meanwhile admixtures have become common practice in concrete technology, but the understanding of these highly complex polymers in the entire concrete system lags far behind their application. Due to its complex time-dependent, multi-phase and multi-scale behaviour, flowable concrete systems are highly complicated and cannot be described comprehensively by simple models. It is therefore extremely challenging to identify the relevant parameters that predominantly control flow phenomena on different size scales, since these may occur on any scale between the nano scale (e.g. superplasticizer adsorption) and macro scale (e.g. grading of the aggregates). The present study discusses fundamental mechanisms at the interface between particle or hydrate surfaces and the fluid phase at a very early stage of concrete formation, and links these effects to macroscopic flow phenomena. Methods are discussed that appear promising interdisciplinary tools for enhancement of the understanding of the relevant interactions that are responsible for the macroscopic flow of flowable concrete. T2 - 8th International RILEM Symposium on Self-Compacting Concrete CY - Washington, D.C., USA DA - 15.05.2016 KW - Adsorption KW - Analytics KW - Hydration KW - Polycarboxylate ether KW - Rheology PY - 2016 SP - 245 EP - 254 AN - OPUS4-36882 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - AFM an Polymer- und Faseroberflächen T2 - Institut für Textil- und Faserchemie, Universität Stuttgart CY - Stuttgart, Germany DA - 1996-11-12 PY - 1996 AN - OPUS4-6397 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heyde, M. A1 - Sturm, Heinz T1 - SPM Techniques to characterise Electrical Properties of Nanometer sized Particles T2 - Raster-Sonden-Mikroskopien und organische Materialien VII CY - Berlin, Germany DA - 1998-10-07 PY - 1998 AN - OPUS4-6455 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Rasterkraftmikroskopie mit Leitfähigkeitskontrast T2 - Tagung "Raster-Sonden-Methoden und Organische Materialien" am Europäischen Lab. für Molekularbiologie CY - Heidelberg, Germany DA - 1994-10-11 PY - 1994 AN - OPUS4-6372 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Rastersondenverfahren: Materialkontraste und Nanolithographie T2 - DGM Fachausschuss "Gefüge und Eigenschaften von Polymerwerkstoffen" CY - Berlin, Germany DA - 2003-12-05 PY - 2003 AN - OPUS4-2917 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - An AFM-ESEM hybrid instrument T2 - BAM Symposium "Polymere Verbundwerkstoffe zwischen Raumtemperatur und 4,2K" CY - Berlin, Germany DA - 2003-02-27 PY - 2003 AN - OPUS4-4095 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Methods for simultaneous measurements of topography and local electrical properties using scanning force microscopy T2 - 9th International Symposium on Electrets (ISE9) CY - Shanghai, China DA - 1996-09-15 PY - 1996 AN - OPUS4-6396 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Robust plasmonic substrates T2 - E-MRS 2013 Spring Meeting CY - Strasbourg, France DA - 2013-05-21 PY - 2013 AN - OPUS4-28487 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - From microstructures to nanodots: AFM experiments with a piezoelectric polymer T2 - iThemba LABS CY - Somerset West, South Africa DA - 2002-02-03 PY - 2002 AN - OPUS4-6527 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Studies of wear on materials by SPM T2 - Workshop em Microscopiy de Forca Atomica e tecnicas correlatas CY - Rio de Janeiro, Brazil DA - 1997-10-14 PY - 1997 AN - OPUS4-6423 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - SFM of Polymers with Harmonically Modulated Friction Force T2 - 24th Intern. TopoMetrix-Workshop: Aktuelle Entwicklungen in der Nanotechnologie und der Rastersondenmikroskopie, Humboldt-Universität CY - Berlin, Germany DA - 1998-03-12 PY - 1998 AN - OPUS4-6459 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Prinzipien der Rastersondenmikroskopie T2 - Vortrag am Institut für Nichtmetallische Werkstoffe der TU Berlin CY - Berlin, Germany DA - 2005-11-03 PY - 2005 AN - OPUS4-11315 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Munz, Martin A1 - Sturm, Heinz A1 - Stark, Wolfgang T1 - Mechanical gradient interphase by interdiffusion and antiplasticisation effect - study of an epoxy/thermoplastic system N2 - A stoichiometric amine–epoxy formulation was cured in the presence of a thermoplastic, namely poly(vinylpyrrolidone) (PVP). The epoxy system consisted of the resin diglycidyl ether of bisphenol A (DGEBA) and the aromatic curing agent 4,4'-diaminodiphenylsulfone (DDS). As shown for this system in a former study by Oyama et al. [Oyama HT, Lesko JJ, Wightman JP. J Polym Sci B 1997;35:331–46. [36]], preferential absorption of amine molecules by PVP can occur. In the present study, the focus is on the variations of local elastic properties within the epoxy interphase adjacent to the PVP layer. The curing was performed close to the glass transition temperature, Tα, of the PVP film, namely at 170 °C. Variations of the local amine concentration were tracked using energy-dispersive analysis of X-rays (EDX), by taking benefit of the sulfur contained in DDS. Using temperature-dependent dynamic mechanical analysis (DMA), a series of epoxy reference samples of different amine–epoxy concentration ratios, r, was investigated in order to work out the relationship between r and the epoxy storage modulus at room temperature. In the excess-epoxy regime, r<1, the modulus is observed to increase with departure from the stoichiometric ratio, r=1. Considering the respective suppression of the ß-transition, the observed characteristic can be explained by an antiplasticisation effect. Depth-sensing indentation (DSI) experiments across the epoxy/PVP interphase provided evidence for strong modulus variations. In consistency with the EDX and the DMA data, in the vicinity of the PVP layer the local epoxy modulus is increased. The total change of the epoxy Young's modulus is ~1.1 GPa. However, the total width of the modulus decay of ~175 µm is ~2.5 times larger than the one of the DDS concentration gradient. This finding is discussed in terms of additional spatial variations of the DGEBA concentration as well as long-range diffusion currents of DDS induced by the interdiffusion processes and their effect on the final network of crosslinks. KW - Interdiffusion KW - Interphase/interface KW - Polymer PY - 2005 DO - https://doi.org/10.1016/j.polymer.2005.06.098 SN - 0032-3861 SN - 1873-2291 VL - 46 IS - 21 SP - 9097 EP - 9112 PB - Springer CY - Berlin AN - OPUS4-10893 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tavasolyzadeh, Zeynab A1 - Tang, Peng A1 - Hahn, Marc Benjamin A1 - Hweidi, Gada A1 - Nordholt, Niclas A1 - Haag, Rainer A1 - Sturm, Heinz A1 - Topolniak, Ievgeniia T1 - 2D and 3D Micropatterning of Mussel‐Inspired Functional Materials by Direct Laser Writing N2 - AbstractThis work addresses the critical need for multifunctional materials and substrate‐independent high‐precision surface modification techniques that are essential for advancing microdevices and sensing elements. To overcome existing limitations, the versatility of mussel‐inspired materials (MIMs) is combined with state‐of‐the‐art multiphoton direct laser writing (DLW) microfabrication. In this way, 2D and 3D MIM microstructures of complex designs are demonstrated with sub‐micron to micron resolution and extensive post‐functionalization capabilities. This study includes polydopamine (PDA), mussel‐inspired linear, and dendritic polyglycerols (MI‐lPG and MI‐dPG), allowing their direct microstructure on the substrate of choice with the option to tailor the patterned topography and morphology in a controllable manner. The functionality potential of MIMs is demonstrated by successfully immobilizing and detecting single‐stranded DNA on MIM micropattern and nanoarray surfaces. In addition, easy modification of MIM microstructure with silver nanoparticles without the need of any reducing agent is shown. The methodology developed here enables the integration of MIMs in advanced applications where precise surface functionalization is essential. KW - Direct laser writing KW - Mussel-inspired materials KW - Polyglycerol KW - Polydopamine KW - Micropatterning PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-588778 DO - https://doi.org/10.1002/smll.202309394 SN - 1613-6829 SP - 1 EP - 12 PB - Wiley-VCH CY - Weinheim AN - OPUS4-58877 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cappella, Brunero A1 - Geuss, Markus A1 - Sturm, Heinz A1 - Heyde, M. A1 - Rademann, K. A1 - Spangenberg, T. A1 - Niehus, H. T1 - Dynamic plowing nanolithography on polymethylmethacrylate using an atomic force microscope N2 - We present dynamic plowing nanolithography on polymethylmethacrylate films, performed with a scan-linearized atomic force microscope able to scan up to 250 μm with high resolution. Modifications of the surface are obtained by plastically indenting the film surface with a vibrating tip. By changing the oscillation amplitude of the cantilever, i.e., the indentation depth, surfaces can be either imaged or modified. A program devoted to the control of the scanning process is also presented. The software basically converts the gray scale of pixel images into voltages used to control the dither piezo driving cantilever oscillations. The advantages of our experimental setup and the dependence of lithography efficiency on scanning parameters are discussed. Some insights into the process of surface modifications are presented. KW - Nanolithography PY - 2001 UR - http://rsi.aip.org/ DO - https://doi.org/10.1063/1.1326053 SN - 0034-6748 SN - 1089-7623 VL - 72 SP - 136 EP - 141 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-874 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fankhänel, J. A1 - Silbernagl, Dorothee A1 - Ghasem Zadeh Khorasani, Media A1 - Daum, B. A1 - Kempe, A. A1 - Sturm, Heinz A1 - Rolfes, R. T1 - Mechanical properties of Boehmite evaluated by Atomic Force Microscopy experiments and Molecular Dynamic Finite Element simulations N2 - Boehmite nanoparticles show great potential in improving mechanical properties of fiber reinforced polymers. In order to predict the properties of nanocomposites, knowledge about the material parameters of the constituent phases, including the boehmite particles, is crucial. In this study, the mechanical behavior of boehmite is investigated using Atomic Force Microscopy (AFM) experiments and Molecular Dynamic Finite Element Method (MDFEM) simulations. Young’s modulus of the perfect crystalline boehmite nanoparticles is derived from numerical AFM simulations. Results of AFM experiments on boehmite nanoparticles deviate significantly. Possible causes are identified by experiments on complementary types of boehmite, that is, geological and hydrothermally synthesized samples, and further simulations of imperfect crystals and combined boehmite/epoxy models. Under certain circumstances, the mechanical behavior of boehmite was found to be dominated by inelastic effects that are discussed in detail in the present work.The studies are substantiated with accompanying X-ray diffraction and Raman experiments. KW - AFM KW - MDFEM KW - Nanocomposite KW - Epoxy KW - X-ray diffraction KW - Raman spectroscopy KW - Young’s modulus KW - Slippage of weakly linked layers PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-384230 UR - https://www.hindawi.com/journals/jnm/2016/5017213/#B26 DO - https://doi.org/10.1155/2016/5017213 VL - 2016 IS - Article ID 5017213 SP - 1 EP - 13 PB - Hindawi Publishing Corporation AN - OPUS4-38423 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hahn, Marc Benjamin A1 - Meyer, Susann A1 - Schröter, Maria-Astrid A1 - Seitz, H. A1 - Kunte, Hans-Jörg A1 - Solomun, Tihomir A1 - Sturm, Heinz T1 - Direct electron irradiation of DNA in fully aqueous environment. Damage determination in combination with Monte Carlo simulations N2 - We report on a study in which plasmid DNA in water was irradiated with 30 keV electrons generated by a scanning electron microscope and passed through a 100 nm thick Si3N4 membrane. The corresponding Monte Carlo simulations suggest that the kinetic energy spectrum of the electrons throughout the water is dominated by low energy electrons (<100 eV). The DNA radiation damage, single-strand breaks (SSB) and double-strand breaks (DSB), was determined by electrophoresis. The median lethal dose of D1/2 = 1.7 ± 0.3 Gy was found to be much smaller compared to partially or fully hydrated DNA irradiated under vacuum conditions. The ratio of DSB to SSB was found to be (1:12) as compared to 1:88) found for hydrated DNA. Our method enables quantitative measurements of radiation damage to biomolecules (DNA, proteins) in solutions under varying conditions (pH, salinity, cosolutes) for an electron energy range which is difficult to probe by standard methods. KW - Plasmid DNA in water KW - Monte Carlo simulation KW - Low energy electrons KW - DNA radiation damage KW - Single-strand break (SSB) KW - Double-strand break (DSB) KW - Lethal dose KW - Radiation damage to biomolecules KW - Solutions (pH, salinity, cosolutes) PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-386981 DO - https://doi.org/10.1039/C6CP07707B SN - 1463-9076 SN - 1463-9084 VL - 19 IS - 3 SP - 1798 EP - 1805 PB - Royal Society of Chemistry AN - OPUS4-38698 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hahn, Marc Benjamin A1 - Meyer, Susann A1 - Kunte, Hans-Jörg A1 - Solomun, Tihomir A1 - Sturm, Heinz T1 - Measurements and simulations of microscopic damage to DNA in water by 30 keV electrons: A general approach applicable to other radiation sources and biological targets N2 - The determination of the microscopic dose-damage relationship for DNA in an aqueous environment is of a fundamental interest for dosimetry and applications in radiation therapy and protection. We combine geant4 particle-scattering simulations in water with calculations concerning the movement of biomolecules to obtain the energy deposit in the biologically relevant nanoscopic volume. We juxtaposition these results to the experimentally determined damage to obtain the dose-damage relationship at a molecular level. This approach is tested for an experimentally challenging system concerning the direct irradiation of plasmid DNA (pUC19) in water with electrons as primary particles. Here a microscopic target model for the plasmid DNA based on the relation of lineal energy and radiation quality is used to calculate the effective target volume. It was found that on average fewer than two ionizations within a 7.5-nm radius around the sugar-phosphate backbone are sufficient to cause a single strand break, with a corresponding median lethal energy deposit being E1/2=6±4 eV. The presented method is applicable for ionizing radiation (e.g., γ rays, x rays, and electrons) and a variety of targets, such as DNA, proteins, or cells. KW - DNA KW - Radiation damage KW - Dosimetry KW - DNA radiation damage KW - Single-strand break (SSB) KW - Double-strand break (DSB) KW - Low energy electrons KW - Monte Carlo simulation KW - Radiation damage to biomolecules KW - Plasmid DNA in water KW - Lethal dose KW - Solutions (pH, salinity, cosolutes) KW - Geant4 KW - Microdosimetry PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-404244 DO - https://doi.org/10.1103/PhysRevE.95.052419 SN - 2470-0045 SN - 2470-0053 VL - 95 IS - 5 SP - 052419-1 EP - 052419-8 PB - American Physical Society CY - USA AN - OPUS4-40424 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hahn, Marc Benjamin A1 - Susann, Meyer A1 - Schröter, Maria-Astrid A1 - Kunte, Hans-Jörg A1 - Solomun, Tihomir A1 - Sturm, Heinz T1 - DNA protection by ectoine from ionizing radiation: molecular mechanisms N2 - Ectoine, a compatible solute and osmolyte, is known to be an effective protectant of biomolecules and whole cells against heating, freezing and extreme salinity. Protection of cells (human keratinocytes) by ectoine against ultraviolet radiation has also been reported by various authors, although the underlying mechanism is not yet understood. We present the first electron irradiation of DNA in a fully aqueous environment in the presence of ectoine and at high salt concentrations. The results demonstrate effective protection of DNA by ectoine against the induction of single-strand breaks by ionizing radiation. The effect is explained by an increase in low-energy electron scattering at the enhanced free-vibrational density of states of water due to ectoine, as well as the use of ectoine as an ˙OH-radical scavenger. This was demonstrated by Raman spectroscopy and electron paramagnetic resonance (EPR). KW - Ectoine KW - DNA KW - Radiation protection KW - Ionizing radiation KW - Compatible solute KW - Biomolecules KW - Sodium chloride KW - Aqueous solution KW - Hydroxyectoine KW - Raman spectroscopy KW - Electron irradiation KW - Cancer KW - Radical scavenger KW - Low energy electrons KW - Hydroxyl radical KW - OH-radical KW - Ectoin KW - UV radiation KW - Sun KW - Salt KW - Radiation therapy PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-419332 UR - http://pubs.rsc.org/en/content/articlehtml/2017/cp/c7cp02860a DO - https://doi.org/10.1039/C7CP02860A SN - 1463-9076 VL - 19 IS - 37 SP - 25717 EP - 25722 PB - Royal Society of Chemistry CY - United Kingdom AN - OPUS4-41933 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stajanca, Pavol A1 - Mihai, L. A1 - Sporea, D. A1 - Negut, D. A1 - Sturm, Heinz A1 - Schukar, Marcus A1 - Krebber, Katerina ED - Webb, D. J. ED - Scully, P. ED - Sugden, K. T1 - Impacts of gamma irradiation on cytop plastic optical fibres N2 - Impact of gamma radiation on transmission of a commercial Cytop polymer optical fibre (Lucina, Asahi Glass Company) is investigated. Spectral dependence of radiation induced attenuation in the investigated fibre is measured in the VIS-NIR spectral region. Besides attenuation increase, radiation is found to increase fibre susceptibility to water as well. While pristine Cytop fibre is rather humidity insensitive, strong humidity related absorption in the NIR region is observed after fibre irradiation. Selective irradiation of separate fibre sections is proposed as a way of fibre humidity sensitization and quasi-distributed water detection is demonstrated using optical time domain reflectometry at 1310 nm. T2 - POF 2016: 25th International Conference on Plastic Optical Fibres CY - Birmingham, UK DA - 13.09.2016 KW - Polymer optical fibers KW - Cytop KW - Gamma radiation PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-403216 SN - 9781854494085 SP - 114 EP - 117 CY - Birmingham AN - OPUS4-40321 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröter, Maria-Astrid A1 - Ritter, M. A1 - Holschneider, M. A1 - Sturm, Heinz T1 - Enhanced DySEM imaging of cantilever motion using artificial structures patterned by focused ion beam techniques N2 - We use a dynamic scanning electron microscope (DySEM) to map the spatial distribution of the vibration of a cantilever beam. The DySEM measurements are based on variations of the local secondary electron signal within the imaging electron beam diameter during an oscillation period of the cantilever. For this reason, the surface of a cantilever without topography or material variation does not allow any conclusions about the spatial distribution of vibration due to a lack of dynamic contrast. In order to overcome this limitation, artificial structures were added at defined positions on the cantilever surface using focused ion beam lithography patterning. The DySEM signal of such high-contrast structures is strongly improved, hence information about the surface vibration becomes accessible. Simulations of images of the vibrating cantilever have also been performed. The results of the simulation are in good agreement with the experimental images. KW - FIB patterning KW - Structured cantilever KW - AFM KW - Modal analysis KW - DySEM PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-354510 DO - https://doi.org/doi:10.1088/0960-1317/26/3/035010 VL - 26 IS - 3 SP - 035010-1 EP - 035010-7 AN - OPUS4-35451 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hahn, Marc Benjamin A1 - Uhlig, F. A1 - Solomun, Tihomir A1 - Smiatek, J. A1 - Sturm, Heinz T1 - Combined influence of ectoine and salt: spectroscopic and numerical evidence for compensating effects of aqueous solutions N2 - Ectoine is an important osmolyte, which allows microorganisms to survive in extreme environmental salinity. The hygroscopic effects of ectoine in pure water can be explained by a strong water binding behavior whereas a study on the effects of ectoine in salty solution is yet missing. We provide Raman spectroscopic evidence that the influence of ectoine and NaCl are opposing and completely independent of each other. The effect can be explained by the formation of strongly hydrogen-bonded water molecules around ectoine which compensate the influence of the salt on the water dynamics. The mechanism is corroborated by first principles calculations and broadens our understanding of zwitterionic osmolytes in aqueous solution. Our findings allow us to provide a possible explanation for the relatively high osmolyte concentrations in halotolerant bacteria. KW - Ectoine KW - Aqueous solution KW - Biological structure KW - Organic osmolytes KW - Raman spectroscopy KW - Water structure PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-376761 UR - http://pubs.rsc.org/en/content/articlelanding/2016/cp/c6cp05417j#!divAbstract DO - https://doi.org/10.1039/c6cp05417j VL - 18 IS - 41 SP - 28398 EP - 28402 PB - Royal Society of Chemistry CY - UK AN - OPUS4-37676 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Breitenbach, Romy A1 - Silbernagl, Dorothee A1 - Toepel, J. A1 - Sturm, Heinz A1 - Broughton, William J. A1 - Sassaki, G. L. A1 - Gorbushina, Anna T1 - Corrosive extracellular polysaccharides of the rock-inhabiting model fungus Knufia petricola N2 - Melanised cell walls and extracellular polymeric matrices protect rock-inhabiting microcolonial fungi from hostile environmental conditions. How extracellular polymeric substances (EPS) perform this protective role was investigated by following development of the model microcolonial black fungus Knufia petricola A95 grown as a sub-aerial biofilm. Extracellular substances were extracted with NaOH/formaldehyde and the structures of two excreted polymers studied by methylation as well as NMR analyses. The main polysaccharide (~ 80%) was pullulan, also known as α-1,4-; α-1,6-glucan, with different degrees of polymerisation. Αlpha-(1,4)-linked-Glcp and α-(1,6)-linked-Glcp were present in the molar ratios of 2:1. A branched galactofuromannan with an α-(1,2)-linked Manp main chain and a β-(1,6)-linked Galf side chain formed a minor fraction (~ 20%). To further understand the roles of EPS in the weathering of minerals and rocks, viscosity along with corrosive properties were studied using atomic force microscopy (AFM). The kinetic viscosity of extracellular K. petricola A95 polysaccharides (≈ 0.97 × 10-6 m2 s-1) ranged from the equivalent of 2% (w/v) to 5% glycerine, and could thus profoundly affect diffusion-dominated processes. The corrosive nature of rock-inhabiting fungal EPS was also demonstrated by its effects on the aluminium coating of the AFM cantilever and the silicon layer below. KW - Corrosion KW - EPS KW - Melanised microcolonial fungi (MCF) KW - Pullulan KW - Sub-aerial biofilms (SAB) KW - α-1,4- and α-1,6-glucans KW - AFM cantilever vibration KW - Nanoviscosity KW - Nanocorrosion of aluminium and silicon PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-435910 DO - https://doi.org/10.1007/s00792-017-0984-5 SN - 1433-4909 SN - 1431-0651 VL - 22 IS - 2 SP - 165 EP - 175 PB - Springer CY - Berlin AN - OPUS4-43591 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ghasem Zadeh Khorasani, Media A1 - Silbernagl, Dorothee A1 - Platz, D. A1 - Sturm, Heinz T1 - Insights into Nano-Scale Physical and Mechanical Properties of Epoxy/Boehmite Nanocomposite Using Different AFM Modes N2 - Understanding the interaction between nanoparticles and the matrix and the properties of interphase is crucial to predict the macroscopic properties of a nanocomposite system. Here, we investigate the interaction between boehmite nanoparticles (BNPs) and epoxy using different atomic force microscopy (AFM) approaches. We demonstrate benefits of using multifrequency intermodulation AFM (ImAFM) to obtain information about conservative, dissipative and van der Waals tip-surface forces and probing local properties of nanoparticles, matrix and the interphase. We utilize scanning kelvin probe microscopy (SKPM) to probe surface potential as a tool to visualize material contrast with a physical parameter, which is independent from the mechanics of the surface. Combining the information from ImAFM stiffness and SKPM surface potential results in a precise characterization of interfacial region, demonstrating that the interphase is softer than epoxy and boehmite nanoparticles. Further, we investigated the effect of boehmite nanoparticles on the bulk properties of epoxy matrix. ImAFM stiffness maps revealed the significant stiffening effect of boehmite nanoparticles on anhydride-cured epoxy matrix. The energy Dissipation of epoxy Matrix locally measured by ImAFM shows a considerable increase compared to that of neat epoxy. These measurements suggest a substantial alteration of epoxy structure induced by the presence of boehmite. KW - Nanomechanics KW - Intermodulation-AFM KW - Interphase KW - Boehmite KW - Epoxy PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-476040 DO - https://doi.org/10.3390/polym11020235 SN - 2073-4360 VL - 11 IS - 2 SP - 235, 1 EP - 19 PB - MDPI AN - OPUS4-47604 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kirner, Sabrina V. A1 - Slachciak, Nadine A1 - Elert, Anna Maria A1 - Griepentrog, Michael A1 - Fischer, Daniel A1 - Hertwig, Andreas A1 - Sahre, Mario A1 - Dörfel, Ilona A1 - Sturm, Heinz A1 - Pentzien, Simone A1 - Koter, Robert A1 - Spaltmann, Dirk A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Tribological performance of titanium samples oxidized by fs-laser radiation, thermal heating, or electrochemical anodization N2 - Commercial grade-1 titanium samples (Ti, 99.6%) were treated using three alternative methods, (i) femtosecond laser processing, (ii) thermal heat treatment, and (iii) electrochemical anodization, respectively, resulting in the formation of differently conditioned superficial titanium oxide layers. The laser processing (i) was carried out by a Ti:sapphire laser (pulse duration 30 fs, central wavelength 790 nm, pulse repetition rate 1 kHz) in a regime of generating laser-induced periodic surface structures (LIPSS). The experimental conditions (laser fluence, spatial spot overlap) were optimized in a sample-scanning setup for the processing of several square-millimeters large surface areas covered homogeneously by these nanostructures. The differently oxidized titanium surfaces were characterized by optical microscopy, micro Raman spectroscopy, variable angle spectroscopic ellipsometry, and instrumented indentation testing. The tribological performance was characterized in the regime of mixed friction by reciprocating sliding tests against a sphere of hardened steel in fully formulated engine oil as lubricant. The specific tribological performance of the differently treated surfaces is discussed with respect to possible physical and chemical mechanisms. KW - Femtosecond laser KW - Titanium KW - Oxidation KW - Friction PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-445609 DO - https://doi.org/10.1007/s00339-018-1745-8 SN - 0947-8396 SN - 1432-0630 VL - 124 IS - 4 SP - 326, 1 EP - 10 PB - Springer-Verlag AN - OPUS4-44560 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröter, Maria-Astrid A1 - Meyer, Susann A1 - Hahn, Marc Benjamin A1 - Solomun, Tihomir A1 - Sturm, Heinz A1 - Kunte, Hans-Jörg T1 - Ectoine protects DNA from damage by ionizing radiation N2 - Ectoine plays an important role in protecting biomolecules and entire cells against environmental stressors such as salinity, freezing, drying and high temperatures. Recent studies revealed that ectoine also provides effective protection for human skin cells from damage caused by UV-A radiation. These protective properties make ectoine a valuable compound and it is applied as an active ingredient in numerous pharmaceutical devices and cosmetics. Interestingly, the underlying mechanism resulting in protecting cells from radiation is not yet fully understood. Here we present a study on ectoine and its protective influence on DNA during electron irradiation. Applying gel electrophoresis and atomic force microscopy, we demonstrate for the first time that ectoine prevents DNA strand breaks caused by ionizing electron radiation. The results presented here point to future applications of ectoine for instance in cancer radiation therapy. KW - Plasmid DNA pUC19 KW - Electron irradiation 30 [kV] KW - Effective irradiation dose 0.2-16 [Gy] KW - Gel electrophoresis KW - AFM intermittent contact KW - Radioprotector ectoine KW - Compatible solute PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-428287 DO - https://doi.org/10.1038/s41598-017-15512-4 SN - 2045-2322 VL - 7 IS - 1 SP - 15272, 1 EP - 15272, 7 PB - Nature AN - OPUS4-42828 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Waegner, M. A1 - Schröder, M. A1 - Suchaneck, G. A1 - Sturm, Heinz A1 - Weimann, Christiane A1 - Eng, L. M. A1 - Gerlach, G. T1 - Domain formation in nano-patterned PZT thin films N2 - In this work, reactive magnetron-sputtered Pb(Zr,Ti)O3 thin films were used to fabricate well-ordered nanodot arrays by means of nanosphere lithography (NSL). NSL is based on a two-step etch process by means of, firstly adjusting the diameter of polystyrene spheres in the self-assembled polymeric nanosphere mask using reactive ion etching, and secondly transferring the mask to the substrate by ion milling with adjusted heights. Hence, structures with different aspect ratios can be fabricated. Piezoresponse force microscopy was used as the inspection tool on both non-patterned and patterned films. Both the topography and polarization out of plane and in plane was deduced in this mode. Grains of nanodots with low aspect ratio form domain structures comparable to domains in non-patterned films. In contrast to that, nanodots with a higher aspect ratio form particular structures. The in-plane amplitude images show mostly a bisectioned domain assembly, while the out-of-plane amplitude images show in some cases more complex structures like 'c'-shaped domains or multi-domains around a center domain. The patterning of the ferroelectric material was shown to affect the formation of ferroelectric domains. The initial polycrystalline, randomly-ordered films are re-oriented and show domain structures depending on nanodisc diameter and aspect ratio. This may enable tailoring of ferroelectric materials in their piezoelectric and pyroelectric properties by patterning. T2 - MRS Spring Meeting 2012 CY - San Francisco, CA, USA DA - 09.04.2012 KW - Nanostructure KW - Piezoresponse KW - Ferroelectric KW - Piezo response force microscopy KW - Nanodots PY - 2012 DO - https://doi.org/10.1557/opl.2012.1230 SN - 1946-4274 SN - 0272-9172 VL - 1454 SP - 267 EP - 272 PB - North-Holland CY - New York, NY AN - OPUS4-26521 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Arlt, C. A1 - Exner, W. A1 - Riedel, U. A1 - Sturm, Heinz A1 - Sinapius, M. ED - Wiedemann, M. ED - Sinapius, M. T1 - Nanoscaled boehmites' modes of action in a polymer and its carbon fiber reinforced plastic N2 - Laminates of carbon fiber reinforced plastic (CFRP), which are manufactured by injection technology, are reinforced with boehmite particles. This doping strengthens the laminates, whose original properties are weaker than those of prepregs. Besides the shear strength, compression strength and the damage tolerance, the mode of action of the nanoparticles in resin and in CFRP is also analyzed. It thereby reveals that the hydroxyl groups and even more a taurine modification of the boehmites' surface alter the elementary polymer morphology. Consequently a new flow and reaction comportment, lower glass transition temperatures and shrinkage, as well as a changed mechanical behavior occur. Due to a structural upgrading of the matrix (higher shear stiffness, reduced residual stress), a better fiber-matrix adhesion, and differing crack paths, the boehmite nanoparticles move the degradation barrier of the material to higher loadings, thus resulting in considerably upgraded new CFRP. KW - Nano particles KW - Epoxy KW - Aerospace PY - 2012 SN - 978-3-642-29189-0 SN - 978-3-642-29190-6 DO - https://doi.org/10.1007/978-3-642-29190-6_4 SP - 49 EP - 58 PB - Springer CY - Berlin AN - OPUS4-26496 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - AFM-basierte Nanoanalytik für die Mikrosystemtechnik T2 - Gründungskolloquium des BAM-AK Life Science CY - Berlin, Germany DA - 2003-04-02 PY - 2003 AN - OPUS4-4094 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Solomun, Tihomir A1 - Sturm, Heinz T1 - Bringing electrons and microarray technology together N2 - Low-energy secondary electrons are the most abundant radiolysis species which are thought to be able to attach to and damage DNA via formation and decay of localized molecular resonances involving DNA components. In this study, we analyze the consequences of low-energy electron impact on the ability of DNA to hybridize (i.e., to form the duplex). Specifically, single-stranded thymine DNA oligomers tethered to a gold surface are irradiated with very low-energy electrons (E = 3 eV, which is below the 7.5 eV ionization threshold of DNA) and subsequently exposed to a dye-marked complementary strand to quantify by a fluorescence method the electron induced damage. The damage to (dT)25 oligomers is detected at quite low electron doses with only about 300 electrons per oligomer being sufficient to completely preclude its hybridization. In the microarray format, the method can be used for a rapid screening of the sequence dependence of the DNA-electron interaction. We also show for the first time that the DNA reactions at surfaces can be imaged by secondary electron (SE) emission with both high analytical and spatial sensitivity. The SE micrographs indicate that strand breaks induced by the electrons play a significant role in the reaction mechanism. KW - Low energy electrons KW - DNA hybridization KW - Low voltage SEM KW - Fluorescence PY - 2007 DO - https://doi.org/10.1021/jp075338v SN - 1520-6106 SN - 1089-5647 VL - 111 IS - 36 SP - 10636 EP - 10638 PB - Soc. CY - Washington, DC AN - OPUS4-15840 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Madbouly, Loay Akmal A1 - Sturm, Heinz A1 - Doolin, Alexander A1 - Hodoroaba, Vasile-Dan A1 - Radnik, Jörg T1 - Chemical Analysis of Commercial Functionalized Graphene Nanoplatelets along the Production Process with Raman Spectroscopy and X-ray Photoelectron Spectroscopy N2 - Commercial applications increasingly rely on functionalized graphene nanoplatelets (GNPs) supplied as powders, aqueous suspensions, and printable inks, yet their process−structure−property relationships across the production chain remain to be fully mapped. Here we apply a correlative Raman spectroscopy (Raman) and X-ray photoelectron spectroscopy (XPS) workflow to nine independent industrial graphene batches spanning three surface chemistries, raw (R), fluorinated (F), and nitrogen-functionalized (N), in all three physical forms which are powders, suspensions, and inks. Raman mapping (with a 532 nm excitation laser) showed that I2D/IG is highest for N samples and lowest for R-ink. A 2D-vs-G correlation places all samples on a trajectory parallel to the pure-doping vector, which can correlate to holes in the graphene lattice. The mean point-defect spacing is LD = 8.4−10.0 nm. High-resolution XPS resolves the accompanying chemical changes: F-powder exhibits distinct C−F (289 eV), C−F2 (292 eV), and C−F3 (293 eV) components and loses roughly half its F content upon dispersion in deionized water or ink formulation; inks of all chemistries show a pronounced O−C=O peak near 289−290 eV originated from the ink compounds. N-functionalized samples showed a prominent C−N (285.5 eV) only for the ink formulated N-functionalized sample. This study establishes a process-aware blueprint linking the functionalization route and formulation step to lattice disorder and surface chemistry, offering transferable quality-control metrics for graphene supply chains in industrial products/applications such as coatings, storage devices, and printed electronics. KW - Functionalized graphene KW - Raman Spectroscopy KW - XPS KW - Chemical analysis PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-652548 DO - https://doi.org/10.1021/acs.jpcc.5c06820 SN - 1932-7447 VL - 129 IS - 50 SP - 22033 EP - 22040 PB - American Chemical Society (ACS) AN - OPUS4-65254 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Topolniak, Ievgeniia A1 - Knigge, Xenia A1 - Radnik, Jörg A1 - Sturm, Heinz T1 - Maskless Micropatterning of Polydopamine for versatile surface functionalization N2 - Inspired by the chemistry of mussel adhesive proteins, polydopamine (PDA has been shown as one of the most versatile platforms for altering the properties and incorporating new functionalities to nearby any material surface despite its nature. Rich chemistry of PDA enables broad variety of surface modification and diverse secondary reactions that makes it extremely interesting for a wide range of application including biomedical field, e.g., drug delivery, adhesives, cell adhesion, biosensing. Despite high potential of polydopamine, the lack of deposition control and precision in existed methods limits their applications in microdevices and miniaturized functional systems like, for example, MEMS, microfluidic and sensorics. Herein, we demonstrate a novel maskless approach for surface micropatterning with polydopamine based on Multiphoton Lithography that overcomes present limitations. Neither strong oxidants, metal ions nor adjustment of pH to alkaline is required by this technique. The spatial resolution down to 0.8 µm has been achieved which is at least an order of magnitude smaller than shown by other existed methods. We are able to control the morphology and thickness of the micropattern by altering fabrication parameters allowing structure gradient. Apart from the glass substrate, we achieved PDA patterning at surfaces of different nature such as polychlorotrifluoroethylene, polydimethylsiloxane, polyethylene terephthalate, silicon wafers, and fluorinated glass coverslips. Post-modification of polydopamine micropatterns with protein enzyme like trypsin is demonstrated to highlight its sensing potential. Presented in this work microfabrication technique empowers advanced applications of mussel-inspired materials in single-molecule bioassays, sensors and other complex microdevices. T2 - International Conference on Precision Engineering and Sustainable Manufacturing CY - Okinawa, Japan DA - 18.07.2023 KW - Multiphoton lithography KW - Polydopamine KW - Micropatterning PY - 2023 AN - OPUS4-58878 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Elert, Anna Maria A1 - Chen, Yong-Cin A1 - Smales, Glen Jacob A1 - Topolniak, Ievgeniia A1 - Sturm, Heinz A1 - Schönhals, Andreas A1 - Szymoniak, Paulina T1 - Effects of the charge density of nanopapers based on carboxymethylated cellulose nanofibrils investigated by complementary techniques N2 - Cellulose nanofibrils (CNFs) with different charge densities were prepared and investigated by a combination of different complementary techniques sensitive to the structure and molecular dynamics of the system. The morphology of the materials was investigated by scanning electron microscopy (SEM) and X-ray scattering (SAXS/WAXS). The latter measurements were quantitatively analyzed yielding to molecular parameters in dependence of the charge density like the diameter of the fibrils, the distance between the fibrils, and the dimension of bundles of nanofibrils, including pores. The influence of water on the properties and the charge density is studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and broadband dielectric spectroscopy. The TGA measurements reveal two mass loss processes. The one at lower temperatures was related to the loss of water, and the second process at higher temperatures was related to the chemical decomposition. The resulting char yield could be correlated to the distance between the microfibrils. The DSC investigation for hydrated CNFs revealed three glass transitions due to the cellulose segments surrounded by water molecules in different states. In the second heating scan, only one broad glass transition is observed. The dielectric spectra reveal two relaxation processes. At low temperatures or higher frequencies, the β-relaxation is observed, which is assigned to localized fluctuation of the glycosidic linkage. At higher temperatures and lower frequencies, the α-relaxation takes places. This relaxation is due to cooperative fluctuations in the cellulose segments. Both processes were quantitatively analyzed. The obtained parameters such as the relaxation rates were related to both the morphological data, the charge density, and the content of water for the first time. KW - Cellulose nanofibrils PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600528 DO - https://doi.org/https://doi.org/10.1021/acsomega.4c00255 SN - 2470-1343 VL - 9 SP - 20152 EP - 20166 PB - ACS AN - OPUS4-60052 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fritzsche, Sven A1 - Pauw, Brian Richard A1 - Weimann, Christiane A1 - Sturm, Heinz T1 - First of its kind: A test artifact for direct laser writing N2 - With femtosecond-laser direct writing (fs-LDW) maturing in all aspects as a manufacturing technology, a toolset for quality assurance must be developed. In this work we introduce a first of its kind test artifact. Test artifacts are standardized 3D models with specific geometric features to evaluate the performance of writing parameters. Test artifacts are already common in other 3D additive manufacturing technologies e.g. selective laser melting. The test artifact introduced in this work was developed in particular to accommodate the high geometrical resolution of fs-LDW structures and the limited possibilities to examine the resulting structure. Geometric accuracy, surface adhesion as well as confocal Raman spectroscopy results were considered when evaluating the design of the test artifact. We will explain the individual features and design considerations of our fs-LDW test artifact. The difference between two slicers, Cura and 3DPoli, and the implications on measured feature sizes and the general shape is quantified. The measured geometries are used to derive a general design guide for a specific combination of photoresists, laser power and scanning speed and to analyze the geometric accuracy of a structure produced using these guidelines. The shown test artifact is publicly available as STL file on GitHub (https://github.com/BAMresearch/2PP-TestArtifact) and in the supplement. KW - Laser direct writing KW - Multi photon lithography KW - Reference material KW - Raman spectroscopy KW - Confocal raman imaging KW - Slicers KW - Open data on zenodo PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-580951 DO - https://doi.org/10.1088/1361-6501/acc47a VL - 34 IS - 7 SP - 1 EP - 14 PB - IOP Science AN - OPUS4-58095 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Silbernagl, Dorothee A1 - Szymoniak, Paulina A1 - Tavasolyzadeh, Zeynab A1 - Sturm, Heinz A1 - Topolniak, Ievgeniia T1 - Multiphoton lithography of interpenetrating polymer networks for tailored microstructure thermal and micromechanical properties N2 - Multiphoton lithography (MPL), an emerging truly 3D microfabrication technique, exhibits substantial potential in biomedical applications, including drug delivery and tissue engineering. Fabricated micro-objects are often expected to undergo shape morphing or bending of the entire structure or its parts. Furthermore, ensuring precise property tuning is detrimental to the realization of the functionality of MPL microstructures. Herein, novel MPL materials based on interpenetrating polymer networks (IPNs) are presented that effectively combine the advantages of acrylate and epoxy systems. IPNs with varying component ratios are investigated for their microfabrication performance and structural integrity with respect to thermal and micromechanical properties. A variety of high-resolution techniques is applied to comprehensively evaluate IPN properties at the bulk, micron, and segmental levels. This study shows that the MPL laser scanning velocity and power, photoinitiator content, and multi-step exposure can be used to tune the morphology and properties of the IPN. As a result, a library of 3D MPL IPN microstructures with high 3D structural stability and tailored thermal and micromechanical properties is achieved. New IPN microstructures with Young’s moduli of 3–4 MPa demonstrate high-to-fully elastic responses to deformations, making them promising for applications in morphable microsystems, soft micro-robotics, and cell engineering. KW - Interpenetrating polymer network KW - Multiphoton lithography KW - Atomic force microscopy KW - Intermodulation AFM KW - Fast scanning calorimetry PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600593 DO - https://doi.org/10.1002/smll.202310580 SN - 1613-6810 SP - 1 EP - 12 PB - Wiley-VCH CY - Weinheim AN - OPUS4-60059 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Munz, Martin A1 - Sturm, Heinz T1 - Structure formation on the surface of indium phosphide irradiated by femtosecond laser pulses N2 - Laser-induced periodic surface structures (LIPSS; ripples) with different spatial characteristics have been observed after irradiation of single-crystalline indium phosphide (c-InP) with multiple linearly polarized femtosecond pulses (130 fs, 800 nm) in air. With an increasing number of pulses per spot, N, up to 100, a characteristic evolution of two different types of ripples has been observed, i.e., (i) the growth of a grating perpendicular to the polarization vector consisting of nearly wavelength-sized periodic lines and (ii), in a specific pulse number regime (N = 5-30), the additional formation of equally oriented ripples with a spatial period close to half of the laser wavelength. For pulse numbers higher than 50, the formation of micrometer-spaced grooves has been found, which are oriented perpendicular to the ripples. These topographical surface alterations are discussed in the frame of existing LIPSS theories. KW - Femtosecond laser irradiation KW - Indium phosphide KW - Microstructure KW - Laser induced periodic surface structures KW - LIPSS KW - SEM PY - 2005 DO - https://doi.org/10.1063/1.1827919 SN - 0021-8979 SN - 1089-7550 VL - 97 SP - 1 EP - 9 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-5992 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Technology transfer of a new developed exploratory Scanning Force Microscope, fine-tuned to meet the demands of the upcoming Nanobiotechnology industries T2 - International Forum On Project Development, Industrial Heritage Program CY - Bologna, Italy DA - 2005-02-28 PY - 2005 AN - OPUS4-6976 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Messung elektrischer Eigenschaften in der Rasterkraftmikroskopie: Leitfähigkeitskontrast auf Kohlefaseroberflächen T2 - Tagung "Raster-Sonden-Mikorskopien und organische Materialien IV" CY - Munich, Germany DA - 1995-10-11 PY - 1995 AN - OPUS4-6388 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Analysis of Scanning Probe Microscopy (SPM) Piezos T2 - Digital-Instruments User-Workshop an der TU Dresden CY - Dresden, Germany DA - 1999-04-07 PY - 1999 AN - OPUS4-6498 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Braun, Ulrike A1 - Lorenz, Edelgard A1 - Weimann, Christiane A1 - Sturm, Heinz A1 - Karimov, I. A1 - Ettl, J. A1 - Meier, R. A1 - Wohlgemuth, W. A. A1 - Berger, H. A1 - Wildgruber, M. T1 - Mechanic and surface properties of central-venous port catheters after removal: A comparison of polyurethane and Silicon rubber materials N2 - Central venous port devices made of two different polymeric materials, thermoplastic polyurethane (TPU)and silicone rubber (SiR), were compared due their material properties. Both naïve catheters as well as catheters after removal from patients were investigated. In lab experiments the influence of various chemo-therapeutic solutions on material properties was investigated, where as the samples after removal were compared according to the implanted time inpatient. The macroscopic,mechanical performance was assessed with dynamic, specially adapted tests for elasticity. The degradation status of the materials was determined with common tools of polymer characterisation, such as infrared spectroscopy, molecular weight measurements and various methods of thermal analysis. The surface morphology was an alysed using scanning electron microscopy. A correlation between material properties and clinical performance was proposed. The surface morphology and chemical composition of the polyurethane catheter materials can potentially result in increased susceptibility of the catheter to bloodstream infections and thrombotic complications. The higher mechanic failure,especially with increasing implantation time of the silicone catheters is related to the lower mechanical performance compared to the polyurethane material as well as loss of barium sulphate filler particles near the surface of the catheter. This results in preformed microscopic notches, which act as predetermined sites of fracture. KW - Thermoplastic polyurethane (TPU) KW - Silicone rubber (SiR) KW - Catheters KW - Central venous access port KW - Complication KW - Structure propertyrelationship KW - Mechanical testing PY - 2016 DO - https://doi.org/10.1016/j.jmbbm.2016.08.002 SN - 1751-6161 SN - 1878-0180 VL - 64 SP - 281 EP - 291 PB - Elsevier Ltd. AN - OPUS4-37178 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Munz, Martin A1 - Sturm, Heinz A1 - Schulz, Eckhard A1 - Hinrichsen, G. T1 - The scanning force microscope as a tool for the detection of local mechanical properties within the interphase of fibre reinforced polymers N2 - Scanning force microscopy (SFM) has been used to assess the local mechanical properties of fibre-reinforced polymers. Using a sinusoidal displacement modulation (DM) and lock-in technique the method allows to characterize local viscoelastic properties with a high lateral resolution. The simultaneous measurement of the local electrical conductivity is proposed which facilitates the interpretation of the mechanical data. The investigation of cross-sections perpendicular to the axis of carbon fibres embedded in PPS delivers some information about the change in local stiffness within the interfacial region. As a first approach, assuming a single-exponential decrease in local stiffness along a radial line from fibre to polymer we find characteristic decay lengths which are distributed in a range between 20 and 80nm. Further, a modified DM-mode is proposed which is expected to provide a contrast enhancement of the signal which is related to local stiffness. This can be achieved by installing an additional feedback loop which keeps constant the amplitude of dynamic indentation (CDI-mode). KW - Polymer-matrix composites (PMC´s) KW - Interface/interphase KW - SFM/AFM KW - Surface properties KW - Nondestructive testing PY - 1998 DO - https://doi.org/10.1016/S1359-835X(98)00077-3 SN - 1359-835X VL - 29 SP - 1251 EP - 1259 PB - Elsevier CY - Oxford AN - OPUS4-1294 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Sturm, Heinz A1 - Geuss, Markus A1 - Schulz, Eckhard ED - Konsta, A. T1 - Scanning force microscopy investigations on electroactive polymer films N2 - The authors present investigations on a PVDF (polyvinylidenefluoride) film supplied with top and bottom Au electrodes, which is analysed using a SFM and a contactless optical sensor to measure the sample strain with respect to applied fields. T2 - 10th IEEE International Symposium on Electrets (ISE) CY - Delphi, Greece DA - 1999-09-22 PY - 1999 SN - 0-7803-5025-1 DO - https://doi.org/10.1109/ISE.1999.832086 SP - 465 EP - 468 PB - IEEE Operations Center CY - Piscataway, NJ AN - OPUS4-6862 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - AFM cantilevers as mechanical sensors T2 - Nano-Seminar am NanoSYD-Institut der süddänischen Universität in Sonderborg CY - Sonderborg, Denmark DA - 2008-12-02 PY - 2008 AN - OPUS4-18266 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Solomun, Tihomir A1 - Schimanski, A. A1 - Sturm, Heinz A1 - Illenberger, E. T1 - Reactions of amide group with fluorine as revealed with surface analytics N2 - Thin polyamide-6 films were exposed to fluorine gas and analysed with photoelectron and infrared spectroscopies. Fluorine cleaves the amide C–N bond resulting in the formation of the –COOH and –NF2 terminal groups. This is evident from large shifts in the N1s binding energy (+5 eV) and C=O stretching frequency (~80 cm-1), appearance of ester oxygen in the XPS spectra, as well as by the 19F nmr spectra of volatile products consistent with a terminal NF2 group. KW - Gasfluorierung KW - Polyamid-6 KW - XPS KW - IR KW - -COOH und NF2-Gruppen PY - 2004 UR - http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235231%232004%23996109995%23499295%23FLA%23&_cdi=5231&_pubType=J&_auth=y&_acct=C000049503&_version=1&_urlVersion=0&_userid=963821&md5=baea8e0df63660c666921ef377c00e40 SN - 0009-2614 SN - 1873-4448 VL - 378 SP - 312 EP - 316 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-3439 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Solomun, Tihomir A1 - Seitz, H. A1 - Sturm, Heinz T1 - DNA damage by low-energy electron impact: dependence on guanine content KW - DNA oligonucleotide KW - Low energy electrons KW - Secondary electrons KW - Damage KW - Guanine content PY - 2009 DO - https://doi.org/10.1021/jp905263x SN - 1520-6106 SN - 1089-5647 VL - 113 IS - 34 SP - 11557 EP - 11559 PB - Soc. CY - Washington, DC AN - OPUS4-20704 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Nichtlinearität und Hysterese von AFM-Piezos T2 - 24th Intern. TopoMetrix-Workshop: Aktuelle Entwicklungen in der Nanotechnologie und Rastersondenmikroskopie, Humboldt-Universität CY - Berlin, Germany DA - 1998-03-12 PY - 1998 AN - OPUS4-6462 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Lithography on Polymers using a Scanning Force Microscope (SFM) and a Environmental Scanning Electron Microscope (ESEM) T2 - Seminar International PhD Program CY - Berlin, Germany DA - 2004-04-30 PY - 2004 AN - OPUS4-3504 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Rastersondenverfahren T2 - BAM, DGM Fachausschuss "Gefüge und Eigenschaften von Polymerwerkstoffen" CY - Berlin, Germany DA - 2003-12-05 PY - 2003 AN - OPUS4-4099 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Dynamics of phase transitions in polymer thin films upon single femtosecond laser pulse irradiation T2 - Second International Conference on Photo-Induced Phase Transitions Cooperative, non-linear and functional properties CY - Rennes, France DA - 2005-05-24 PY - 2005 AN - OPUS4-7430 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sturm, Heinz A1 - Schulz, Eckhard T1 - Atomic force microscopy with simultaneous AC conductivity contrast for the analysis of carbon fibre surfaces KW - Carbon fibre KW - Surface analysis KW - Conductivity microscopy KW - Scanning force microscopy KW - Scanning tunneling microscopy KW - Fiber surfaces PY - 1996 SN - 1359-835X VL - 27 IS - 9 SP - 677 EP - 684 PB - Elsevier CY - Oxford AN - OPUS4-6849 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Munz, Martin A1 - Sturm, Heinz A1 - Schulz, Eckhard T1 - Zuverlässigkeit von Polymer-Werkstoffen - Interphasen nanoskopisch betrachtet T2 - 3. Workshop "Rasterkraftmikroskopie in der Werkstoffwissenschaft" CY - Berlin, BAM, Deutschland DA - 2002-02-28 PY - 2002 SP - 14 AN - OPUS4-1831 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Lithographie, Manipulation und Analyse in ESEM und AFM T2 - Evaluierungsmeeting eines zukünftigen DFG-Forscherverbundes zum Thema "Nanoröhren und -drähte" CY - Halle (Saale), Germany DA - 2003-01-17 PY - 2003 AN - OPUS4-2915 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Atomic force microscopy with simultaneous AC conductivity contrast for the analysis of carbon fibre surfaces T2 - IPCM (Interfacial Phenomena in Composite Materials) CY - Eindhoven, Netherlands DA - 1995-09-10 PY - 1995 AN - OPUS4-6385 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dümichen, Erik A1 - Javdanitehran, M. A1 - Erdmann, Maren A1 - Trappe, Volker A1 - Sturm, Heinz A1 - Braun, Ulrike A1 - Ziegmann, G. T1 - Analyzing the network formation and curing kinetics of epoxy resins by in situ near-infrared measurements with variable heating rates N2 - Near-infrared spectroscopy (NIR) turned out to be well suited for analyzing the degree of cure for epoxy systems. In contrast to dynamic scanning calorimetry (DSC), where the released heat of reaction determines the degree of epoxy conversion indirectly, NIR spectroscopy is able to determine the conversion directly by analyzing structural changes. Therefore, a new heatable NIR cell was equipped with an integrated thermocouple, which enables the real sample temperature to be controlled and monitored in situ during epoxy curing. Dynamic scans at different heating rates were used for kinetic modelling, to define kinetic parameters and to predict real curing processes. The kinetic models and their parameters were validated with an isothermal and a more complex multi-step curing scenario. Two available commercial epoxy systems based on DGEBA were used with an anhydride and with an amine hardener. NIR results were compared with DSC data. The simulated conversion predicted with a model fitted on the basis of NIR and DSC dynamic scans showed good agreement with the conversion measured in the isothermal curing validation test. Due to the proven reliability of NIR in measuring the reaction progress of curing, it can be considered a versatile measurement system for in situ monitoring of component production in the automotive, aerospace and wind energy sectors. KW - Epoxy resins KW - Curing kinetics KW - Near-infrared spectroscopy KW - DSC PY - 2015 DO - https://doi.org/10.1016/j.tca.2015.08.008 SN - 0040-6031 SN - 1872-762X VL - 616 SP - 49 EP - 60 PB - Elsevier CY - Amsterdam AN - OPUS4-34187 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz A1 - Kovalev, Alexander T1 - Nanotribologie an explosionsfähigen Kristallen N2 - Energetische Materialien enthalten gespeicherte chemische Energie. Diese potentielle Energie kann bei Zündung schlagartig als Strahlungsenergie und Druckerhöhung freigesetzt werden. Nanoskalige Komponenten erhöhen zusätzlich die innere Energie des Materials um den Beitrag der Oberflächenenergie und verbessern die chemische Umsetzung durch bessere Durchmischung. Die hot-spot-Theorie zur Zündung von Explosivstoffen kombiniert mechanische Stimulation und einer dabei zu erreichenden Schwellwert-Energie mit der Temperatur. Wird die Energie zum exothermen Bindungsbruch etwa beim Reibvorgang erreicht entsteht auf der molekularen Skala ein hot-spot. Der Stoff explodiert, wenn der hot-spot ausreichend lange besteht, sich verstärkt und nicht durch Energiedissipation (Festkörperschallausbreitung, Wärmediffusion) verzehrt wird. Rasterkraftmikroskopie (AFM – atomic force microscopy) dient nicht nur zur bildgebenden Vermessung der Topographie und der mechanischen Eigenschaften, sondern kann auch zur gezielten Veränderung der Oberflächen verwendet werden. Solche lithographischen Verfahren bedienen sich im AFM-Kontaktmodus (Scratching Lithography) direkt der Reibung, im hochfrequenten intermittierenden Kontaktverfahren realisiert man einen vibrierenden Kontaktes (Dynamic Plowing Lithography), der beim Eindringen in eigenen Indentationseindruck reibt. In beiden Fällen überträgt man durch Kombination einer Scherbewegung mit einer Variation des Kontaktdrucks Energie auf die Oberfläche, was nachweislich zum chemischen Bindungsbruch z.B. auf Polymeroberflächen führt. Zwei kristalline Explosivstoffe werden untersucht und sowohl dissipative Effekte als auch die Generierung eines hot-spots demonstriert. N2 - Using nanoscale components increase the internal energy by the contribution of surface energy and improve the progress of the chemical reaction. The hot-spot theory of ignition describes the conversion of mechanical energy of friction or impact into heat, leading to exothermal decomposition of the explosive. Thus, it is evident that ignition should be studied on the nanoscale and atomic force microscopy (AFM) provides one of the best solutions to study such behavior. AFM, often used to map a topography image and local mechanical properties on a surface, can also be utilized for carrying lithography, namely scratching lithography or dynamic plowing lithography. In both cases shear stress combined with a variation of contact pressure transfers sufficient energy into the surface to break chemical bonds. Two crystalline explosives are investigated and dissipative processes as well as hot-spot generation are described. During the nanotribological test, the in-situ restructuring of molecular layers under ambient conditions was observed and recorded. T2 - 54. Tribologie-Fachtagung - Reibung, Schmierung und Verschleiß - Forschung und praktische Anwendungen CY - Göttingen, Germany DA - 30.09.2013 KW - Energetische Kristalle KW - Hot spot Theorie PY - 2013 SN - 978-3-00-022603-8 IS - Paper 39 SP - 39/1 EP - 39/11 AN - OPUS4-29457 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Der dynamische Reibkontrast als eine Methode zur Charakterisierung von Polymeroberflächen in der Rasterkraftmikroskopie T2 - Frühjahrstagung der DPG, FA: Polymerphysik CY - Münster, Germany DA - 1997-03-17 PY - 1997 AN - OPUS4-6415 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heyde, M. A1 - Sturm, Heinz A1 - Rademann, K. T1 - New application for the calibration of scanning probe microscopy piezos KW - Scanning probe microscope KW - Piezoelectric translator KW - Calibration KW - Height Calibration KW - Force-Microscopy PY - 1999 SN - 0142-2421 SN - 1096-9918 VL - 27 IS - 5-6 SP - 291 EP - 295 PB - Wiley CY - Chichester AN - OPUS4-6858 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Nanoröhren und -drähte - Lithographie, Manipulation und Analyse in ESEM und AFM T2 - Vorbereitungstreffen zum DFG Schwerpunkt "Nanodrähte und Nanoröhren" CY - Halle (Saale), Deutschland DA - 2003-01-17 PY - 2003 CY - Halle AN - OPUS4-2130 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Studies of wear on materials by SPM T2 - First Workshop on Scanning Probe Microscopy CY - São Carlos, Brazil DA - 1997-10-10 PY - 1997 AN - OPUS4-6421 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fichera, Mario Augusto A1 - Braun, Ulrike A1 - Schartel, Bernhard A1 - Sturm, Heinz A1 - Knoll, Uta A1 - Jäger, Christian T1 - Solid-state NMR investigations of the pyrolysis and thermo-oxidative decomposition products of a polystyrene/red phosphorus/magnesium hydroxide system N2 - Thermal, thermo-oxidative and fire residues of high impact polystyrene/magnesium hydroxide/red phosphorus (HIPS/Mg(OH)2/Pr) are investigated by solid-state NMR and compared with the results for the binary subsystem Mg(OH)2/Pr. The influences of oxygen, nitrogen and temperature are discussed. For a thermal decomposition and pyrolysis during combustion, the main pyrolysis of HIPS takes place while the remaining residue is a rather intact polymer, with a major share of the embedded Pr still present. Subsequently, mainly amorphous phosphates and a slight amount of crystalline Mg3(PO4)2 and Mg2P2O7 are formed at the highest temperatures. Only with increasing mass loss does the remaining polystyrene structure decompose and graphitic structures occur. The influence of oxygen on the decomposition mechanism is most obvious for the binary system Mg(OH)2/Pr. Pr vanishes more rapidly and crystalline, oxygen-rich magnesium phosphates are formed. In HIPS/Mg(OH)2/Pr systems the polymer acts as a barrier to reaction by the embedded particles, so that major characteristics of an anaerobic decomposition are found. Significant amounts of phosphorus are retained in the condensed phase through a reaction of Pr with Mg(OH)2 to mostly amorphous phosphates. This formation of amorphous inorganic magnesium phosphates can act as an additional physical barrier. This study outlines some advanced approaches for controlling the condensed-phase mechanisms of phosphorus and underlines that solid-state NMR is a most powerful tool for investigating the organic and inorganic residues. KW - HIPS KW - Red phosphorus KW - Magnesium hydroxide KW - Solid-state NMR KW - Flame retarded polymers PY - 2007 SN - 0165-2370 SN - 1873-250X VL - 78 IS - 2 SP - 378 EP - 386 PB - Elsevier CY - Amsterdam AN - OPUS4-14517 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Nanomechanics in Scanning Force Microscopy (SFM) T2 - 1st Latin American Symposium on Scanning Probe Microscopy (LA SPM1) CY - São Carlos, Brazil DA - 2001-03-29 PY - 2001 AN - OPUS4-6515 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Topolniak, Ievgeniia A1 - Elert, Anna Maria A1 - Knigge, Xenia A1 - Ciftci, G. C. A1 - Radnik, Jörg A1 - Sturm, Heinz T1 - High precision micropatterning of polydopamine by Multiphoton Lithography N2 - Mussel-inspired polydopamine (PDA) initiated a multifunctional modification route that leads to the generation of novel advanced materials and their applications. However, existing PDA deposition techniques still exhibit poor spatial control, have a very limited capability of micropatterning and do not allow to locally tune PDA topography. Herein, we demonstrate PDA deposition based on Multiphoton Lithography (MPL) that enables full spatial and temporal control with nearly total freedom of patterning design. Using MPL, we achieve 2D microstructures of complex design with pattern precision of 0.8 μm without the need of a photomask or stamp. Moreover, this approach permits adjusting the morphology and thickness of the fabricated microstructure within one deposition step, resulting in a unique tunability of materials properties. The chemical composition of PDA is confirmed and its ability for protein enzyme immobilization is demonstrated. This work presents a new methodology for high precision and complete control of PDA deposition, enabling PDA incorporation in applications where fine and precise local surface functionalization is required. Possible applications include multicomponent functional elements and devices in microfluidics or lab-on-a-chip systems. KW - Multiphoton lithography KW - Polydopamine KW - Micropatterning PY - 2022 DO - https://doi.org/10.1002/adma.202109509 VL - 34 IS - 18 SP - e2109509 PB - Wiley online library AN - OPUS4-54535 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Topolniak, Ievgeniia A1 - Elert, Anna Maria A1 - Knigge, Xenia A1 - Cifci, G. C. A1 - Radnik, Jörg A1 - Sturm, Heinz T1 - Polydopamine micropatterning for selective substrate bio-functionalization N2 - Inspired by the chemistry of mussel adhesive proteins, polydopamine (PDA) exhibits strong adhesion to nearly any kind of organic or inorganic surface and shows high ability for surface post-modification and secondary reactions. As a result, PDA has been widely used as a base adlayer to enable versatile surface chemistry and functionalization. It has shown great potential in wide range of applications including biomedical field (e.g., drug delivery, adhesives, photothermal therapy, bone and tissue engineering, cell adhesion, biosensing). However, implementation of PDA in microdevices is still hindered by insufficient spatial and temporal control of excited deposition methods. In this work we present a novel approach to fabricate tunable micropatterned substrates where mussel-inspired chemistry provides base for various surface modification [2]. Current approach applies Multiphoton Lithography (MPL) to initiate local PDA formation, and, therefore, does not require use of microstamp or photomask. As a result, the microstructures of complex designs can be produced with the spatial resolution down to 0.8 μm (Figure 1). The desired design can be easily altered by adjusting the stl model or the fabrication code. Unlike the conventional deposition of PDA based on dopamine auto-oxidation, our method does not require presence of strong oxidants, metal ions or alkaline pH. Herein-demonstrated deposition approach will significantly facilitate applications of polydopamine and other mussel-inspired materials in microdevices and high-resolution active microcomponents (e.g., in MEMS and microfluidics). Adjustment of MPL parameters revealed that the morphology and thickness of resulted PDA microstructures can be controlled by altering the laser power and its scanning velocity. As a result, it also enables the production of micropatterns with structural gradient. Apart from the glass substrate, we performed PDA patterning at surfaces of different nature such as polychlorotrifluoroethylene, polydimethylsiloxane, polyethylene terephthalate, silicon wafers, and fluorinated glass coverslips. We tested different composition of dopamine solution for its ability of PDA buildup. Solutions containing Tris buffer, phosphate buffer or DI water only as well as different pH (6.0, 7.0 and 8.5) could be successfully applied for high-precision PDA micropatterning. Moreover, the effect of antioxidants and purging of the solution with oxygen and nitrogen was investigated. In all cases, no decrease of deposition efficiency was observed. The chemical nature of PDA was confirmed by locally recorded vibrational and x-ray photoelectron spectra. To ensure post-modification potential of MPL deposited PDA we demonstrated one-step deposition of micropatterns with trypsin. Obtained bio-functionalised surface can be further applied as a protein sensing active microelement. T2 - Laser Precision Microfabrication CY - Dresden, Germany DA - 07.06.2022 KW - Polydopamine KW - Two-photon polymerisation KW - Micropatterning PY - 2022 AN - OPUS4-55064 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fortini, Renata A1 - Meyer-Plath, A. A1 - Kehren, D. A1 - Gernert, U. A1 - Agudo Jácome, Leonardo A1 - Sturm, Heinz T1 - Measurement of flexural rigidity of multi-walled carbon nanotubes by Dynamic Scanning Electron Microscopy N2 - In this work the flexural rigidity of individual large diameter multi-walled carbon nanotubes (MWCNTs) was investigated. The bending modulus were obtained by detecting the resonance frequencies of mechanically excited cantilevered carbon nanotubes using the so-called dynamic scanning electron microscopy technique, and applying the Euler–Bernoulli beam theory. For the nanotubes studied, we determined a modulus of up to 160 GPa. This agrees with values reported by other authors for MWCNTs produced by catalytic chemical vapor deposition, however, it is 6-8 times smaller than values reported for single and multi-walled carbon nanotubes produced by arc-discharge synthesis. Toxicological studies with carbon nanotubes have been showing that inhaled airborne nanofibers that reach the deep airways of the respiratory system may lead to serious, asbestos-like lung diseases. These studies suggested that their toxicity critically depends on the fiber flexural rigidity, with high rigidity causing cell lesions. To complement the correlation between observed toxicological effects and fiber rigidities, reliable and routinely applicable measurement techniques for the flexural rigidity of nanofibers are required. KW - Flexural rigidity KW - Bending modulus KW - Resonance frequency KW - Carbon nanotubes KW - Fiber toxicology PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-514190 DO - https://doi.org/10.3390/fib8050031 SN - 2079-6439 VL - 8 IS - 5 SP - 31 PB - MDPI AN - OPUS4-51419 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Silbernagl, Dorothee A1 - Ghasem Zadeh Khorasani, Media A1 - Cano Murillo, Natalia A1 - Elert, Anna Maria A1 - Sturm, Heinz ED - Glatzel, T. T1 - Bulk chemical composition contrast from attractive forces in AFM force spectroscopy N2 - A key application of atomic force microscopy (AFM) is the measurement of physical properties at sub-micrometer resolution. Methods such as force–distance curves (FDCs) or dynamic variants (such as intermodulation AFM (ImAFM)) are able to measure mechanical properties (such as the local stiffness, kr) of nanoscopic heterogeneous materials. For a complete structure–property correlation, these mechanical measurements are considered to lack the ability to identify the chemical structure of the materials. In this study, the measured attractive force, Fattr, acting between the AFM tip and the sample is shown to be an independent measurement for the local chemical composition and hence a complete structure–property correlation can be obtained. A proof of concept is provided by two model samples comprised of (1) epoxy/polycarbonate and (2) epoxy/boehmite. The preparation of the model samples allowed for the assignment of material phases based on AFM topography. Additional chemical characterization on the nanoscale is performed by an AFM/infrared-spectroscopy hybrid method. Mechanical properties (kr) and attractive forces (Fattr) are calculated and a structure–property correlation is obtained by a manual principle component analysis (mPCA) from a kr/Fattr diagram. A third sample comprised of (3) epoxy/polycarbonate/boehmite is measured by ImAFM. The measurement of a 2 × 2 µm cross section yields 128 × 128 force curves which are successfully evaluated by a kr/Fattr diagram and the nanoscopic heterogeneity of the sample is determined. KW - AFM force spectroscopy KW - Composites KW - Principle component analysis KW - Structure–property correlation KW - Van der Waals forces PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520175 DO - https://doi.org/10.3762/bjnano.12.5 SN - 2190-4286 VL - 12 IS - 5 SP - 58 EP - 71 PB - Beilstein Institute CY - Frankfurt am Main AN - OPUS4-52017 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cano Murillo, Natalia A1 - Ghasem Zadeh Khorasani, Media A1 - Silbernagl, Dorothee A1 - Hahn, Marc Benjamin A1 - Hodoroaba, Vasile-Dan A1 - Sturm, Heinz T1 - Nanomechanical study of polycarbonate/boehmite nanoparticles/epoxy ternary composite and their interphases N2 - Thermoplastic modified thermosets are of great interest especially due to their improved fracture toughness. Comparable enhancements have been achieved by adding different nanofillers including inorganic particles such as nanosized boehmite. Here, we present a nanomechanical study of two composite systems, the first comprising a polycarbonate (PC) layer in contact with epoxy resin (EP) and the second consisting of a PC layer containing boehmite nanoparticles (BNP) which is also in contact with an EP layer. The interaction between PC and EP monomer is tested by in situ Fourier transformed infrared (FT-IR) analysis, from which a reaction induced phase separation of the PC phase is inferred. Both systems are explored by atomic force microscopy (AFM) force spectroscopy. AFM force-distance curves (FDC) show no alteration of the mechanical properties of EP at the interface to PC. However, when a PC phase loaded with BNP is put in contact with an epoxy system during curing, a considerable mechanical improvement exceeding the rule of mixture was detected. The trend of BNP to agglomerate preferentially around EP dominated regions and the stiffening effect of BNP on EP shown by spatial resolved measurements of Young's modulus, suggest the effective presence of BNP within the EP phase. KW - Composites KW - Mechanical properties KW - Nanoparticles KW - Thermoplastics KW - Thermosets PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-515965 DO - https://doi.org/10.1002/app.50231 SN - 0021-8995 SN - 1097-4628 VL - 138 IS - 12 SP - 1 EP - 11 PB - Wiley CY - New York, NY AN - OPUS4-51596 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sänger, Johanna Christiane A1 - Pauw, Brian Richard A1 - Sturm, Heinz A1 - Günster, Jens T1 - First time additively manufactured advanced ceramics by using two-photon polymerization for powder processing N2 - Methods and materials are presented here, which enable the manufacturing of fine structures using a 3D-printing method known as two-photon polymerization (2PP). As traditional photolithography methods for structuring ceramic slurries do not function with 2PP, due to light scattering on ceramic particles, a novel water-based photoresist with high ceramic loading of extremely well dispersed ceramic nano particles was developed. This photoresist is basically a ceramic slurry containing a photocurable agent and a photoinitiator to be crosslinkable with the 780 nm wavelength femtosecond laser light source of the 2PP machine. It is demonstrated that it is possible to gain a highly transparent and low viscous slurry suitable for 2PP processing. This work shows the development of the slurry, first printing results and the post-printing processes required to form three dimensional ceramic microstructures consisting of alumina toughened zirconia (ATZ). KW - 3D-printing KW - Two-photon polymerization KW - 2PP KW - Ceramic nano particles KW - Slurry KW - Alumina toughened zirconia KW - ATZ KW - Additive manufacturing KW - SchwarzP cells KW - Nano-ceramic-additive-manufacturing photoresin KW - NanoCAM PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517441 DO - https://doi.org/10.1016/j.oceram.2020.100040 VL - 4 SP - 100040 PB - Elsevier Ltd. AN - OPUS4-51744 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cano Murillo, Natalia A1 - Ghasem Zadeh Khorasani, Media A1 - Silbernagl, Dorothee A1 - Emamverdi, Farnaz A1 - Cacua, K. A1 - Hodoroaba, Vasile-Dan A1 - Sturm, Heinz T1 - Carrier Fibers for the Safe Dosage of Nanoparticles in Nanocomposites: Nanomechanical and Thermomechanical Study on Polycarbonate/Boehmite Electrospun Fibers Embedded in Epoxy Resin N2 - The reinforcing effect of boehmite nanoparticles (BNP) in epoxy resins for fiber composite lightweight construction is related to the formation of a soft but bound interphase between filler and polymer. The interphase is able to dissipate crack propagation energy and consequently increases the fracture toughness of the epoxy resin. Usually, the nanoparticles are dispersed in the resin and then mixed with the hardener to form an applicable mixture to impregnate the fibers. If one wishes to locally increase the fracture toughness at particularly stressed positions of the fiber-reinforced polymer composites (FRPC), this could be done by spraying nanoparticles from a suspension. However, this would entail high costs for removing the nanoparticles from the ambient air. We propose that a fiber fleece containing bound nanoparticles be inserted at exposed locations. For the present proof-of-concept study, an electrospun polycarbonate nonwoven and taurine modified BNP are proposed. After fabrication of suitable PC/EP/BNP composites, the thermomechanical properties were tested by dynamic mechanical analysis (DMA). Comparatively, the local nanomechanical properties such as stiffness and elastic modulus were determined by atomic force microscopy (AFM). An additional investigation of the distribution of the nanoparticles in the epoxy matrix, which is a prerequisite for an effective nanocomposite, is carried out by scanning electron microscopy in transmission mode (TSEM). From the results it can be concluded that the concept of carrier fibers for nanoparticles is viable. KW - Advanced materials KW - Electrospun nanocomposite fiber KW - Nanomechanical charecteisation KW - Nanosafety KW - Epoxy nanocomposites PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-528265 DO - https://doi.org/10.3390/nano11061591 VL - 11 IS - 6 SP - 1591 PB - MDPI CY - CH - 4020 Basel, Switzerland AN - OPUS4-52826 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Waniek, Tassilo A1 - Braun, U. A1 - Silbernagl, Dorothee A1 - Sturm, Heinz T1 - The impact of water released from boehmite nanoparticles during curing in epoxy-based nanocomposites N2 - The enhancing effect on mechanical properties of boehmite (γ-AlOOH) nanoparticles (BNP) in epoxy-based nanocomposites on the macroscopic scale encouraged recent research to investigate the micro- and nanoscopic properties. Several studies presented different aspects relatable to an alteration of the epoxy polymer network formation by the BNP with need for further experiments to identify the mode of action. With FTIR-spectroscopic methods this study identifies interactions of the BNP with the epoxy polymer matrix during the curing process as well as in the cured nanocomposite. The data reveals that not the BNP themselves, but the water released from them strongly influences the curing process by hydrolysis of the anhydride hardener or protonation of the amine accelerator. The changes of the curing processes are discussed in detail. The changes of the curing processes enable new explanation for the changed material properties by BNP discussed in recent research like a lowered glass transition temperature region (Tg) and an interphase formation. KW - Spectroscopy KW - Aluminium oxide hydroxide KW - Glass transition temperature KW - Material chemistry KW - Nanocomposites KW - Structure-property relationship PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527202 DO - https://doi.org/10.1002/app.51006 VL - 138 IS - 39 SP - 51006 PB - Wiley Periodicals LLC CY - Hoboken AN - OPUS4-52720 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fritzsche, Sven A1 - Topolniak, Ievgeniia A1 - Weise, Matthias A1 - Sturm, Heinz T1 - Shape deviations of DLW microstructures in dependency of fabrication parameters N2 - Deep understanding of the effects associated with fabrication parameters and their influence on the resulting structures shape is essential for the further development of direct laser writing (DLW). In particular, it is critical for development of reference materials, where structure parameters are precisely fabricated and should be reproduced with use of DLW technology. In this study we investigated the effect of various fabrication and preparation parameters on the structural precision of interest for reference materials. A well-studied photo-curable system, SZ2080 negative photo-resist with 1 wt.% Michler's ketone (Bis) photo-initiator, was investigated in this work. The correlation between applied laser power, laser velocity, fabrication direction on the deviations in the structure shape were observed by means of white light interferometry microscopy. Moreover, influence of slicing and hatching distances as well as prebake time were studied as function of sample shape. Deviations in the structure form between the theoretically expected and the one detected after DLW fabrication were observed in the range up to 15%. The observed shape discrepancies show the essential importance of fine-tuning the fabrication parameter for reference structure production. KW - Direct laser writing KW - Fabrication parameters KW - Structural precision KW - SZ2080 negative photo-resist KW - White light interferometry microscopy PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-535906 DO - https://doi.org/10.1088/1361-6439/ac2a14 VL - 31 IS - 12 SP - 1 EP - 8 PB - IOP Science AN - OPUS4-53590 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - INPR A1 - Fritzsche, Sven A1 - Pauw, Brian Richard A1 - Weimann, Christiane A1 - Sturm, Heinz T1 - First of its kind: A test artifact for direct laser writing N2 - With Direct Laser Writing (DLW) maturing in all aspects as a manufacturing technology a toolset for quality assurance must be developed. In this work we want to introduce a first of its kind test artifact. Test artifacts are standardized 3D models with specific geometric feature to evaluate the performance of writing parameters. Test artifacts are already common in other 3D additive manufacturing technologies e.g. Selective Laser Melting. The test artifact introduced in this work was developed in particular to accommodate 1) the high geometrical resolution of DLW structures and 2) the limited possibilities to examine the resulting structure. Geometric accuracy, surface adhesion as well as confocal raman spectroscopy results were considered when evaluating the design of the test artifact. We will explain the individual features and design considerations of our DLW test artifact. The difference between two slicers, Cura and 3DPoli, and the implications on measured feature sizes and the general shape is quantified. The measured geometries are used to derive a general design guide for a specific combination of photoresist, laser power and scanning speed and to analyse the geometric accuracy of a structure produced using these guidelines. KW - Multi photon lithography KW - Test artifact KW - Two photon polymerization KW - Direct Laser Writing KW - Quality infrastructure PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-560530 DO - https://doi.org/10.20944/preprints202210.0259.v1 SP - 1 EP - 29 PB - MDPI CY - Basel AN - OPUS4-56053 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sänger, Johanna Christiane A1 - Pauw, Brian Richard A1 - Riechers, Birte A1 - Zocca, Andrea A1 - Rosalie, Julian A1 - Maaß, Robert A1 - Sturm, Heinz A1 - Günster, Jens T1 - Entering a new dimension in powder processing for advanced ceramics shaping N2 - Filigree structures can be manufactured via two-photon-polymerization (2PP) operating in the regime of non-linear light absorption. For the first time it is possible to apply this technique to the powder processing of ceramic structures with a feature size in the range of the critical defect size responsible for brittle fracture and, thus, affecting fracture toughness of high-performance ceramics. In this way, tailoring of advanced properties can be achieved already in the shaping process. Traditionally, 2PP relies on transparent polymerizable resins, which is diametrically opposed to the usually completely opaque ceramic resins and slurries. Here we present a transparent and photocurable suspension of nanoparticles (resin) with very high mass fractions of yttria-stabilized zirconia particles (YSZ). Due to the extremely well dispersed nanoparticles, scattering of light can be effectively suppressed at the process-relevant wavelength of 800 nm. Sintered ceramic structures with a resolution of down to 500 nm were obtained. Even at reduced densities of 1 to 4 g/cm³, the resulting compressive strength with 4,5 GPa is equivalent or even exceeding bulk monolithic yttria stabilized zirconia. A ceramic metamaterial is born, where the mechanical properties of yttria stabilized zirconia are altered by changing geometrical parameters and gives access to a new class of ceramic materials. KW - Two-photon-polymerization KW - Ceramics KW - Powder processing KW - Transparency KW - Meta material KW - Yttria stabilized zirconia PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-564598 DO - https://doi.org/10.1002/adma.202208653 SN - 1521-4095 SP - 1 EP - 8 PB - Wiley-VCH CY - Weinheim AN - OPUS4-56459 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Silbernagl, Dorothee A1 - Sturm, Heinz A1 - Plajer, A. J. T1 - Thioanhydride/isothiocyanate/epoxide ring-opening terpolymerisation: sequence selective enchainment of monomer mixtures and switchable catalysis N2 - We report a new sequence selective terpolymerisation in which three monomers (butylene oxide (BO) A, PhNCS B and phtalic thioanhydride (PTA) C) are selectively enchained into an (ABA′C)n sequence. PTA/PhNCS/BO ring-opening terpolymerisation ROTERP can be coupled with CS2 ROTERP to generate tetrapolymers and with εDL ROP in switchable catalysis for blockpolymer synthesis. KW - Blockcopolymer KW - 1H-NMR KW - TGA KW - DSC KW - AFM PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-552339 DO - https://doi.org/10.1039/d2py00629d SP - 1 EP - 5 PB - Royal Society of Chemistry CY - Cambridge, UK AN - OPUS4-55233 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Crasselt, Claudia A1 - Schmidt, Wolfram A1 - Sturm, Heinz T1 - Influence of Rheology Modifying Admixtures on Hydration of Cementitious Suspensions N2 - The presence of polycarboxylate ether (PCE) based superplasticizers (SPs) has an enormous influence on the early hydration of cement. The hydration is retarded and the timing of formation and the morphology of hydrates is affected. This short paper presents experimental results about the influence of delayed addition time of PCE SPs on hydration of cement and alite pastes, investigated by isothermal heat flow calorimetry. For cement as well as for alite pastes the hydration is retarded with SP, whereby the high charge PCE has a stronger retarding effect than the low charge PCE. The retardation caused by PCE is much more pronounced for alite than for cement mixes. If PCE is added later to the mix, the induction period is shortened and the hydration is accelerated compared to simultaneous addition. This applies for cement and alite pastes. With delayed PCE addition the alite shows a clearly less retarded setting and main hydration than after simultaneous addition. It is obvious that for alite pastes there is less retardation the later the addition of SP. T2 - 6th International Symposium on Nanotechnology in Construction CY - Hong Kong, China DA - 02.12.2018 KW - Polycarboxylate ether (PCE) KW - Early hydration KW - Cement PY - 2018 SP - 1 EP - 8 AN - OPUS4-47204 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Polymere Faserwerkstoffe und die STM/AFM T2 - Diskussions-Tagung "Raster-Nahfeld-Mikroskopien und organische Materialien" CY - Planegg, Germany DA - 1992-07-08 PY - 1992 AN - OPUS4-6377 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Nanoröhren und -drähte: Lithographie, Manipulation und Analyse in ESEM und AFM T2 - Vorbereitungstreffen zum DFG Schwerpunkt "Nanodrähte und Nanoröhren" CY - Halle (Saale), Germany DA - 2003-01-17 PY - 2003 AN - OPUS4-2914 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Studies of polymers by SPM T2 - First Workshop on Scanning Probe Microscopy CY - São Carlos, Brazil DA - 1997-10-10 PY - 1997 AN - OPUS4-6420 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Der dynamische Reibungskontrast im SFM T2 - Kolloquium der Abt. VI CY - Berlin, Germany DA - 1997-10-23 PY - 1997 AN - OPUS4-6426 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhiem, S. A1 - Barthel, Anne-Kathrin A1 - Meyer-Plath, A. A1 - Hennig, M. P. A1 - Wachtendorf, Volker A1 - Sturm, Heinz A1 - Schäffer, A. A1 - Maes, H. M. T1 - Release of 14C-labelled carbon nanotubes from polycarbonate composites N2 - Waste disposal of carbon nanotube (CNT) containing products is expected to be the most important pathway for release of CNTs into the environment. In the present work, the use of radiolabelled CNTs (14C-CNT) for polycarbonate polymer nanocomposites with 1 wt% 14C-CNT content allowed for the first time to quantify and differentiate the CNT release according to the type of impact along the materials' ageing history. After an initial exposure of the nanocomposite by solar-like irradiation, further environmental impacts were applied to composite material. They aimed at mimicking disposal site conditions that may induce further ageing effects and CNT release. This study included shaking in water, rapid temperature changes, soaking in humic acid solution as well as waste water effluent, and, finally, gentle mechanical abrasion. All ageing impacts were applied sequentially, both on pristine (control) and on solar-irradiated nanocomposites. All experiments were accompanied by absolute quantification of radioactive release as well as chemical and morphological analyses of the nanocomposite surfaces using infra-red (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The morphological analysis showed that spectral irradiation can uncover CNT networks on the outer nanocomposite surface layers by polymer degradation. After having subjected the solar-irradiated nanocomposite to all studied disposal site effect, the total radioactive release was quantified to amount to 64 mg CNT/m2, whereas only 0.8 mg CNT/m2 were found for the un-irradiated control sample. Solar degradation of polymers was thus found to significantly increase the propensity of the studied polymer nanocomposites to release CNTs during ageing effects at the product's end-of-life typical for disposal sites. KW - Weathering KW - Carbon nanotubes KW - Nanocomposites KW - Release KW - Quantification PY - 2016 UR - http://www.sciencedirect.com/science/article/pii/S0269749116303748 DO - https://doi.org/10.1016/j.envpol.2016.04.098 SN - 0269-7491 VL - 215 IS - August SP - 356 EP - 365 PB - Elsevier Ltd. CY - Paris AN - OPUS4-36899 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hartmann, S. A1 - Shaporin, A. A1 - Hermann, S. A1 - Bonitz, J. A1 - Heggen, M. A1 - Meszmer, P. A1 - Sturm, Heinz A1 - Hölck, O. A1 - Blaudeck, T. A1 - Schulz, S. E. A1 - Mehner, J. A1 - Gessner, T. A1 - Wunderle, B. T1 - Towards nanoreliability of CNT-based sensor applications: Investigations of CNT-metal interfaces combining molecular dynamics simulations, advanced in situ experiments and analytics N2 - In this paper we present results of our recent efforts to understand the mechanical interface behaviour of single-walled carbon nanotubes (CNTs) embedded in metal matrices. We conducted experimental pull-out tests of CNTs embedded in Pd or Au and found Maximum forces in the range 10 - 102 nN. These values are in good agreement with forces obtained from molecular Dynamics simulations taking into account surface functional Groups (SFGs) covalently linked to the CNT material. The dominant failure mode in experiment is a CNT rupture, which can be explained with the presence of SFGs. To qualify the existence of SFGs on our used CNT material, we pursue investigations by means of fluorescence labeling of surface species in combination with Raman imaging. We also report of a tensile test system to perform pull-out tests inside a transmission electron microscope to obtain in situ images of CNT-metal interfaces under mechanical loads at the atomic scale. T2 - 2015 16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems CY - Budapest, Hungary DA - 20.4.2015 KW - Carbon nanotube CNT KW - Metal matrix KW - Pull-out test KW - Molecular dynamics simulation KW - Surface functional groups KW - Fluorescence labeling KW - Raman imaging KW - Tensile test inside a TEM PY - 2015 SN - 978-1-4799-9950-7 VL - 2015 SP - 1 EP - 8 PB - IEEE AN - OPUS4-37625 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Das AFM als Werkzeug in der Tribologie: Elementare Reibereignisse, Partikelmanipulation und Lithographie T2 - GDCh-Kolloq. am Institute of Polymer Science, Johannes Kepler University CY - Linz, Austria DA - 2009-06-09 PY - 2009 AN - OPUS4-19551 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Munz, Martin A1 - Sturm, Heinz ED - Bhushan, B. T1 - Nanomechanical Characterization of Structural and Pressure-Sensitive Adhesives KW - Scanning Force Microscopy KW - Modulated Lateral Force Microscopy KW - Stiffness KW - Friction KW - Interface/Interphase Interdiffusion PY - 2007 SN - 3-540-37320-9 DO - https://doi.org/10.1007/978-3-540-37321-6_8 VL - 7 SP - 301 EP - 347 PB - Springer CY - Berlin AN - OPUS4-14974 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Modulated lateral force microscopy: An AFM tool for analysis and modification of polymer surfaces T2 - Nano-Seminar am NanoSYD-Institut der Süddänischen Universität CY - Sonderborg, Denmark DA - 2007-10-11 PY - 2007 AN - OPUS4-18131 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - AFM investigations of surface properties of 2,4,6 trinitrophenol (TNP) crystal at the nanoscale T2 - Frühjahrstagung der Deutschen Physikalischen Gesellschaft CY - Berlin, Germany DA - 2012-03-25 PY - 2012 AN - OPUS4-27339 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Techniques for surface composition analysis with Scanning Force Microscopy (SFM) T2 - ECASIA '97 CY - Gothenburg, Sweden DA - 1997-06-16 PY - 1997 AN - OPUS4-6416 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Rasternahfeldmikroskopie an Oberflächen organischer Werkstoffe T2 - Vortrag für die AFM/STM User Group Berlin-Brandenburg CY - Berlin, Germany DA - 1993-11-30 PY - 1993 AN - OPUS4-6379 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Scanning Force Microscopy based Lithography T2 - Anwendertreffen JPK Instruments CY - Berlin, Germany DA - 2003-09-18 PY - 2003 AN - OPUS4-2916 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Erweiterung konventioneller Rasterkraftmikroskopie: Informationen aus Zusatzkontrasten lokaler elektrischer Eigenschaften T2 - Institut für Physik an der Universität Basel CY - Basel, Switzerland DA - 1994-11-14 PY - 1994 AN - OPUS4-6373 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Rastersondenmikroskopie zur Oberflächenanalyse polymerer Werkstoffe T2 - BAM CY - Berlin, Germany DA - 1994-11-02 PY - 1994 AN - OPUS4-6375 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dümichen, Erik A1 - Braun, Ulrike A1 - Senz, R. A1 - Fabian, G. A1 - Sturm, Heinz T1 - Assessment of a new method for the analysis of decomposition gases of polymers by a combining thermogravimetric solid-phase extraction and thermal desorption gas chromatography mass spectrometry N2 - For analysis of the gaseous thermal decomposition products of polymers, the common techniques are thermogravimetry, combined with Fourier transformed infrared spectroscopy (TGA–FTIR) and mass spectrometry (TGA–MS). These methods offer a simple approach to the decomposition mechanism, especially for small decomposition molecules. Complex spectra of gaseous mixtures are very often hard to identify because of overlapping signals. In this paper a new method is described to adsorb the decomposition products during controlled conditions in TGA on solid-phase extraction (SPE) material: twisters. Subsequently the twisters were analysed with thermal desorption gas chromatography mass spectrometry (TDS–GC–MS), which allows the decomposition products to be separated and identified using an MS library. The thermoplastics polyamide 66 (PA 66) and polybutylene terephthalate (PBT) were used as example polymers. The influence of the sample mass and of the purge gas flow during the decomposition process was investigated in TGA. The advantages and limitations of the method were presented in comparison to the common analysis techniques, TGA–FTIR and TGA–MS. KW - TDS-GC-MS KW - TGA-FTIR KW - TGA-MS KW - Degradation KW - Polymer KW - Solid-phase extraction PY - 2014 DO - https://doi.org/10.1016/j.chroma.2014.05.057 SN - 0021-9673 VL - 1354 SP - 117 EP - 128 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-31046 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Polte, J. A1 - Polte, M. A1 - Lorenz, D. A1 - Oberschmidt, D. A1 - Sturm, Heinz A1 - Uhlmann, E. T1 - Binderless-cBN as cutting material for ultra-precision machining of stainless steel N2 - The ultra–precision cutting of steel materials is possible but needs modifications of machine tools or the workpiece material. One approach of actual research is the development of cutting materials that gives the opportunity for direct cutting of surfaces with ultra–precision quality. Binderless–cBN is here one of the most promising materials. The paper shows results of experimental studies with binderless–cBN as cutting material while turning stainless steel. Various investigations were carried out to determine the wear mechanisms. Furthermore, measurements are shown regarding the surface quality. The achieved results show the high potential ofbinderless–cBN as cutting material for the machining of steel. KW - Cubic boron nitride KW - Stainless steel KW - Ultra-precision PY - 2014 DO - https://doi.org/10.4028/www.scientific.net/AMR.1018.107 SN - 1022-6680 SN - 1662-8985 VL - 1018 SP - 107 EP - 114 PB - Trans Tech Publ. CY - Zurich AN - OPUS4-32377 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Charakterisierung und Strukturierung von nm-Bereichen in Polymer-Werkstoffen - Ein AFM-ESEM-EBL-Hybridsystem T2 - BAM-Sonderheft 2003 "Polymere Verbundwerkstoffe zwischen Raumtemperatur und 4,2 K" ; 2. Symposium im DFG-Projekt: Eigenschaften von PTFE- und PEEK-Matrix-Werkstoffen bei tribologischer Beanspruchung CY - Berlin, Deutschland DA - 2003-02-27 PY - 2003 SP - 58 EP - 59 AN - OPUS4-2673 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Messung lokaler elektrischer Eigenschaften mit dem AFM: Der Leitfähigkeitskontrast T2 - Festvortragsreihe "Fortschritte in der Rastersondenmikroskopie" anläßlich der Eremittierung von Prof. Dr. Lacmann CY - Braunschweig, Germany DA - 1995-03-16 PY - 1995 AN - OPUS4-6383 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Entwicklung und Aufbau eines Rasterkraftmikroskops für lithographische Zwecke in der Nanobiotechnologie T2 - 7. Dresdner Sensor-Symposium, Fachsitzung Nanobiotechnologie CY - Dresden, Germany DA - 2005-12-12 PY - 2005 AN - OPUS4-11481 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Kovalev, Alexander A1 - Sturm, Heinz ED - Wang, Q.J. ED - Chung, Y.-W. T1 - Polymer Adhesion N2 - Polymer adhesion is the phenomenon of adhesive-bonded joint formation between polymer material and other solids brought into contact. KW - Adhesion KW - Polymer KW - Contact interaction PY - 2013 SN - 978-0-387-92896-8 SN - 978-0-387-92897-5 SN - 978-0-387-92898-2 DO - https://doi.org/10.1007/978-0-387-92897-5_816 IS - Chapter C SP - 2551 EP - 2556 PB - Springer Science + Business Media CY - New York AN - OPUS4-28972 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Recipes for the Calibration of Piezos with a Fibre Optical Displacement Sensor for Scanning Probe Microscopy Usage T2 - 10th International Symposium on Electrets (ISE 10) CY - Delphi, Greece DA - 1999-09-22 PY - 1999 AN - OPUS4-6501 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz T1 - Nanotribologie an explosionsfähigen Kristallen T2 - Symposium Nanotribologie im Rahmen der Tribologie Fachtagung der GfT CY - Göttingen, Germany DA - 2013-09-30 PY - 2013 AN - OPUS4-29291 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -