TY - CONF A1 - Saloga, Patrick E. J. T1 - Do non-thermal effects exist? - Microwave-assisted acceleration of silver nanoparticle synthesis and particle growth N2 - Ever since increasing a reaction’s yield while shortening the reaction time is the main objective in synthesis optimization. Microwave reactors meet these demands. In literature however their usage is under discussion due to claims of the existence of non-thermal effects resulting from the microwave radiation. Especially for nano-material syntheses it is of crucial importance to be aware of influences on the reaction pathway. Therefore, we compare ultra-small silver nanoparticles with mean radii of 3 nm, synthesized via conventional and microwave heating. We employed a versatile one-pot polyol synthesis of poly(acrylic acid) (PAA) stabilized silver nanoparticles, which display superior catalytic properties. No microwave specific effects in terms of particle size distribution characteristics, as derived by small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS), are revealed. Due to the microwave reactor’s characteristics of a closed system, syntheses can be carried out at temperatures beyond the solvent’s boiling point. Particle formation was accelerated by a factor of 30 by increasing the reaction temperature from 200 °C to 250 °C. The particle growth process follows a cluster coalescence mechanism. A post-synthetic incubation step at 250 °C induces a further growth of the particles while the size distribution broadens. Thus, utilization of microwave reactors enables an enormous decrease of the reaction time as well as the opportunity of tuning the particles’ size. Possibly, decomposition of the stabilizing ligand at elevated temperatures results in reduced yields. A temperature of 250 °C and a corresponding reaction time of 30 s represent a compromise between short reaction times and high yields. T2 - 5th Nano Today Conference CY - Waikoloa Village, HI, USA DA - 06.12.2017 KW - Microwave synthesis KW - Small-angle scattering KW - Silver nanoparticles PY - 2017 AN - OPUS4-43497 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine T1 - On the sliding behavior of PAEK composites in vacuum environment N2 - The tribological behavior of PAEK composites were investigated in air and vacuum environment. Results indicate that the tribological performance of these compounds depends on material compositions, fiber orientation as well as test conditions. In vacuum, very low friction and wear coefficient were obtained at low sliding speed while severe wear occurred at high speed. T2 - The 6th World Tribology Congress - WTC 2017 CY - Beijing, China DA - 17.09.2017 KW - PAEK KW - Sliding performances KW - Vacuum PY - 2017 AN - OPUS4-42447 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tschiche, Harald T1 - Determination of degradation products of thermoplastic polyurethane using fluorescent sensors in a model system N2 - Polyurethanes (PU) are formed by polyaddition reaction between diols and diisocyantes. They can be formed utilizing three building blocks, namely a polyol or long-chain diol, a chain extender or short-chain diol, and a diisocyanate. The derived multi-phase block copolymer has thermoplastic properties and is called thermoplastic PU (TPU). This modular approach allows for a variety of alternations yielding a broad range of structural properties and applications. TPUs are based on three main classes of polyols, i.e. polyethers, polyesters, and polycaprolactones. With these different polyols and the ability of changing the ratio of building blocks a variety of material properties can be obtained thus TPUs find numerous applications in e.g. lightweight construction1, insulation, flame retardants, lacquer and glue, as well as medicine. Linear, isocyanate terminated, polyurethane prepolymers prepared from non-equivalent amounts of diisocyanate such as methylene diphenyl diisocyanate (MDI) attached to a polyol are widely used as precursors of the correspondent polymers. Chain-extending reactions with low molecular weight compounds bearing different amounts of active hydrogens enable both linear and crosslinked polyurethane to be formed. Due to TPUs being used in a broad range of applications facing a variety of stress (e.g. mechanical, hydrolytic, thermal, radiative/UV, as well as its combinations) the complexity of possible degradation mechanism is high. A functional group derived from degradation of the bulk matrix can be detected utilizing a suited fluorogenic sensor molecule. There are several fluorogenic dyes known for the application as sensor for amine groups e.g. fluorescamine, pyrylium dyes, deriving a fluorescent signal upon reaction. T2 - ANAKON 2017 CY - Tübingen, Germany DA - 03.04.2017 KW - Bewitterung KW - Polyurethan KW - Functional group detection KW - Polyurethanes PY - 2017 AN - OPUS4-40262 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kulla, Hannes T1 - In situ investigations of a mechanochemical cocrystal formation by X-ray diffraction for two different milling jar materials N2 - Mechanochemistry has become a valuable method for the synthesis of new materials, especially for pharmaceutical cocrystals. The Advantages of fast reactions in high purity and yield face a lack of understanding the underlying mechanism. Therefore, in situ setups to study mechanochemical reactions have been established. Herein, we present an in situ investigation of the mechanochemical cocrystal formation of pyrazinamide (PZA) with pimelic acid (PM) using synchrotron XRD. Two new polymorphs of PZA:PM (1:1) were synthesized by milling the starting materials in milling jars of different materials. While Form I is only obtained using a steel jar, Form II can be obtained purely in jars made of Perspex. In situ XRD experiments reveal a direct formation of Form II in Perspex and an intermediate formation of Form II in steel jars converting to Form I upon further grinding. Heating experiments and DFT calculations predict that Form II is the thermodynamically more stable polymorph. Therefore, the reaction progress in the steel jar contradicts Ostwald’s rules of stages as the more stable Form II converts into the metastable Form I. Hence, mechanochemistry offers the possibility to synthesize new materials that cannot be obtained using conventional methods. T2 - Adlershofer Forschungsforum 2017 CY - HU-Berlin, Erwin-Schrödinger Zentrum, Germany DA - 10.11.2017 KW - Cocrystal KW - Mechanochemistry KW - Polymorph KW - In situ KW - Milling PY - 2017 AN - OPUS4-42956 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Piedada, F. M. T1 - Polymorphism in Simvastatin: A Single Crystal X-ray Diffraction, Themodynamic, and MDSimulation Study N2 - Simvastatin is a prominent member of the statin family, a class of antilipidemic drugs widely used in the treatment of high plasma cholesterol levels, and thus in the prevention of atherosclerosis and cardiovascular diseases. Simvastatin is typically employed as a solid and it is well known that, in this case, the detection and characterization of polymorphism is of considerable importance. Polymorphs differ by their packing arrangements and also, occasionally, by the conformations of the molecules in the crystal lattice. These structural variations are normally reflected by differences in physical properties, such as solubility and dissolution rate in a given media, which may significantly affect the bioavailability of a drug. The lack of control of polymorphism can, therefore, play havoc with the safe use of a drug. T2 - COST Action CM1402 CY - Lincoln, United Kingdom DA - 26.06.2017 KW - Polymorphism KW - X-ry Diffraction PY - 2017 AN - OPUS4-41252 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nguyen, Thi Yen T1 - Guided crystallization: The influence of solvent and concentration N2 - Theoretical and experimental studies indicate that crystal nucleation can take more complex pathways than expected on the ground of the classical nucleation theory. A direct in situ observation of the different pathways of nucleation from solution is challenging since the paths can be influenced by heterogeneous nucleation sites, such as container walls. The custom-made acoustic levitator using in these experiments regulates the influence that solid surfaces, temperature, and humidity have on the crystallization process. The investigations of the crystallization process of paracetamol were performed with in situ analytical techniques and theoretical simulations to gain a comprehensive insight into processes, occurring intermediates, and required reaction conditions. The targeted choice of the solvent and the concentration enabled the guidance of the pathways, therefore, resulting in the isolation of one desired crystalline structure. T2 - Annual COST meeting CY - Lincoln, United Kingdom DA - 25.06.2017 KW - Crystallization KW - Polymorphism KW - Molecular dynamic simulation KW - Pair distribution function analysis KW - XRD PY - 2017 AN - OPUS4-41111 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Castro, R. A. E. T1 - New cocrystals of bexarotene with pyridinecarboxamide isomers sustained by the acid∙∙∙aromatic nitrogen supramolecular heterosynthon N2 - Pharmaceutical cocrystals are homogenous crystalline structures made up of two or more components in a definite stoichiometric ratio, where at least one of the components in the crystal lattice is an active pharmaceutical ingredient (API).1 Pharmaceutical cocrystals have opened the opportunity for engineering solid-state forms designed to have tailored properties to enhance drug product bioavailability and stability, as well a enhance processability of the solid material inputs in drug product manufacture. In this work the cocrystallization of bexarotene, an approved API by the U.S. Food and Drug Administration that belongs to Biopharmaceutics Classification System Class II (low solubility–high permeability), with pyridine carboxamide isomers (picolinamide, nicotinamide and isonicotinamide) was successfully undertaken. The synthesis was achieved by liquid assisted grinding (LAG) and the solids obtained were characterized by differential scanning calorimetry (DSC), infrared spectroscopy (FTIR-ATR), powder X-ray diffraction (XRPD), single crystal X-ray diffraction (SXD), and polarized light thermomicroscopy (PLTM). For bexarotene: picolinamide and bexarotene:isonicotinamide, 1:1 cocrystals were obtained directly from milling. SXD data of bexarotene:isonicotinamide cocrystal reveal acid∙∙∙aromatic nitrogen supramolecular heterosynthon and that the homosynthon amide∙∙∙amide in isonicotinamide is preserved. The bexarotene:nicotinamide mixtures prepared by ball milling give rise to simple binary solid–liquid phase diagram with an eutectic point, well described by the Schröder-van Laar equation. Melt crystallization of the 1:1 mixture gives rise to a cocrystal for which a complex phase behaviour is observed. T2 - 6th Meeting IAPC CY - Zagreb, Croatia DA - 04.09.2017 KW - Crystalline structure KW - Bexarotene KW - Powder X-ray diffraction KW - Single crystal X-ray diffraction KW - Infrared spectroscopy PY - 2017 AN - OPUS4-41063 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nützmann, Kathrin T1 - Depth dependent phase identification of corrosion zones in ferritic alloys by micro-X-ray absorption near edge structure spectroscopy N2 - Ferritic steels with chromium contents up to 13 wt% are used as materials for power plant components as boiler materials (< 2 wt% Cr) and super heater tubes (> 9 wt% Cr). These materials are subject to aggressive corrosion caused by hot gases such as CO2, H2O, O2 and SO2. Especially SO2 causes fatal corrosion even as a minor component. To examine sulfurous corrosion mechanisms, experiments with pure SO2 were conducted. A proper analysis of the material changes requires phase identification and quantification with a high lateral resolution within the corrosion scale. T2 - ANAKON2017 CY - Tübingen, Germany DA - 03.04.2017 KW - Corosion KW - Steel KW - XANES PY - 2017 AN - OPUS4-40415 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Breitfeld, Steffen T1 - High energy ball milling of a new representative of coordination polymers without organofluorine linkers N2 - Metal organic frameworks and coordination polymers play an important role in different fields of applications. Moreover, particularly fluorinated metal-organic frameworks (FMOFs) are in the focus of interest during the last years. In most cases, fluorine is implemented using perfluorinated organic linkers at the synthesis, usually performed by solvothermal synthesis. However, only few examples are known so far where fluorine is coordinated directly to the metal cation. Recently, we reported about mechanochemical syntheses and characterization of fluorine-containing coordination polymers of alkaline earth metals by milling M(OH) (M: Ca, Sr, Ba) with fluorinated benzene dicarboxylic acids 2 and we reported about mechanochemical syntheses of alkaline earth metal fluorides with ammonium fluoride. Now we are reporting about a combination of both synthesis routes. That is the first mechanochemical synthesis of coordination polymers where fluorine is coordinated directly to the metal cation. T2 - Konferenz CY - Berlin, Germany DA - 30.11.2017 KW - Metal organic frameworks KW - Coordination polymer KW - Mechanochemical syntheses KW - Direct fluorine-metal bond KW - Alkaline earth metal PY - 2017 AN - OPUS4-46898 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Li, Wei T1 - Crack propagation in filled and unfilled polymers: Separation of surface energy and irreversible deformation energy N2 - Fiber-reinforced-polymers (FRPs) are in current research focus in the lightweight construction industry, because of their extraordinary characteristics (stiffness and strength-to-density relation). The structure of polymer matrix and the interaction with reinforcement are crucial for optimization of the mechanical and thermal properties of FRPs. Due to the macromolecular chain structure, the mechanical properties of a polymer strongly vary with temperature: Below the glass transition, the chain segments of a polymer are “frozen”. Regarding fracture, the total changed energy during fracture if only dissipates for the generation of the new surfaces. However, in the region of the glass transition, the polymer chain segments start to get “unfrozen”, and the energy is not only required for generating new surfaces, but also for irreversibly deformation. This irreversible deformation is affected by the global temperature and the local temperature near the crack tip, which is affected by the local strain rate and crack propagation velocity. Hence, in this research project, the irreversible deformation of neat and reinforced polymers will be controlled by changing the global temperature as well as the local temperature. With using different fracture experiments, the amount of energy required for creating new surfaces and for the irreversible deformation will be separated. The fracture tests include the conventional tensile test, the macroscopic peel test and the single fiber peel – off test. T2 - PhD Day 2018 of BAM CY - Berlin, Germany DA - 31.05.2018 KW - Crack Propagation KW - Polymer PY - 2018 AN - OPUS4-48471 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -