TY - JOUR A1 - Turky, Gamal A1 - Wolff, Dietmar A1 - Schönhals, Andreas T1 - Confinement effects on the molecular dynamics of liquid-crystalline polymethacrylates - a broadband dielectric spectroscopy study N2 - The molecular dynamics of liquid-crystalline polymethacrylates with biphenyl in the side group forming a highly ordered smectic E phase at low temperatures is investigated by dielectric spectroscopy (DS). Although no glass transition is found by DSC, DS detects a relaxation in the smectic E phase resembling to glassy dynamics. The temperature dependence of its relaxation rate is Arrhenius like at low temperatures, which changes to a VFT law at higher temperatures. Such a behavior is found to be characteristic for glassy dynamics in confining space. It is discussed, considering the structure of the polymers as nanobiphasic consisting of liquid-crystalline layers while the backbones fill the interlayer space. A comparison is made to polymethacrylates having phenyl benzoate as mesogen. KW - Dielectric properties KW - Dynamics in confining space KW - Liquid-crystalline polymers KW - Molecular dynamics PY - 2012 DO - https://doi.org/10.1002/macp.201200361 SN - 1022-1352 SN - 1521-3935 VL - 213 IS - 22 SP - 2420 EP - 2431 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-27129 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yildirim, Arda A1 - Haug, T. C. V. A1 - Fröba, M. A1 - Huber, P. A1 - Schönhals, Andreas T1 - Molecular fluctuations in mixed-metal MOF-74: influence of the metal composition N2 - A selected series of metal–organic frameworks M-MOF-74 (M = Mg, Co, Ni) and mixed metal MM-MOF-74 (Mg/Co or Mg/Ni) with different compositions of metal atoms have been prepared and further investigated by broadband dielectric spectroscopy (BDS) in a wide temperature range. The dielectric spectra show at least two relaxation processes. Process-A is observed only for the Ni-containing MOFs and is attributed to localized fluctuations of the metal oxide corners. Relaxation processes-B and -C are observed for all prepared MOFs, except that process-B is not observed for Ni-MOF-74. Large-angle fluctuations such as free rotations of the linkers can be excluded due to the structure of MOF-74, but small-angle fluctuations such as torsions are possible. According to numerical simulations carried out for MOF-74, process-B can be attributed to inward and outward fluctuations of the linkers relative to the pore center. Process-C is related to small-angle rotational fluctuations of the linker together with co-rotations of the metal nodes. The latter interpretation is supported by the dependence of the activation energy of the relaxation rate of process-C on the metal composition of the MOFs, which is discussed in terms of the bond lengths between the metal atoms and the linker which decrease in the sequence Mg, Co and Ni. KW - Metal Organic Frameworks PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639378 DO - https://doi.org/10.1039/d5ra05357a SN - 2046-2069 VL - 15 IS - 35 SP - 29109 EP - 29118 PB - Royal Society of Chemistry (RSC) AN - OPUS4-63937 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kolmangadi, Mohamed A. A1 - Raab, A. R. A1 - Szymoniak, Paulina A1 - Li, Z. A1 - Huber, P. A1 - Laschat, S. A1 - Schönhals, Andreas T1 - Molecular mobility and electrical conductivity of amino acid-based (DOPA) ionic liquid crystals in the bulk state and nanoconfinement N2 - This study explores the molecular mobility, phase behavior, and electrical conductivity of dihydroxyphenylalanine-based ionic liquid crystals (DOPAn, with alkyl side chains n = 12, 14, 16) featuring cyclic guanidiniumchloride headgroups, in both bulk and nanoconfined states. Using broadband dielectric spectroscopy, differential scanning calorimetry, and fast scanning calorimetry, the research uncovers a complex interplay between molecular structure, self-assembly, and molecular mobility. In bulk, DOPAn shows a phase sequence from plastic crystalline to hexagonal columnar and isotropic phases, driven by superdisc formation and columnar organization. Multiple relaxation processes are identified: localized side-chain dynamics (γ-relaxation), ionic headgroup or core motions (α1-relaxation), and cooperative alkyl domain fluctuations (α2-relaxation). Conductivity decreases with increasing side chain length. Under nanoconfinement in anodic aluminum oxide membranes, phase behavior changes: the Colh–Iso transition is suppressed, and a new α3-relaxation appears, linked to dynamics in an adsorbed interfacial layer. DC conductivity drops by up to four orders of magnitude due to confinement effects, altered molecular orientation, and phase transitions—especially the emergence of a nematic-like state in DOPA16. These findings highlight the importance of molecular design, pore geometry, and surface chemistry in tuning ionic liquid crystal properties for advanced applications in nanofluidics, ion transport, and responsive materials. KW - Ionic Liquid Crystals PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639657 DO - https://doi.org/10.1039/d5cp02406d SN - 1463-9084 SP - 1 EP - 17 PB - Royal Society of Chemistry (RSC) AN - OPUS4-63965 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emamverdi, Farnaz A1 - Huang, J. A1 - Mosane Razavi, Negar A1 - Bojdys, M. J. A1 - Forster, A. B. A1 - Budd, P. M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Molecular Mobility and Gas Transport Properties of Mixed Matrix Membranes Based on PIM‑1 and a Phosphinine Containing Covalent Organic Framework N2 - Polymers with intrinsic microporosity (PIMs) are gaining attention as gas separation membranes. Nevertheless, they face limitations due to pronounced physical aging. In this study a covalent organic framework containing λ5-phosphinine moieties, CPSF-EtO were incorporated as a nanofiller (concentration range 0-10 wt%) into a PIM-1 matrix forming dense films with a thickness of ca. 100 μm. The aim of the investigation was to investigate possible enhancements of gas transport properties and mitigating effects on physical aging. The incorporation of the nanofiller occurred on aggregate level with domains up to 100 nm as observed by T-SEM and confirmed by X-ray scattering. Moreover, the X-ray data show that the structure of the microporous network of the PIM-1 matrix is changed by the nanofiller. As the molecular mobility is fundamental for gas transport as well as for physical aging, the study includes dielectric investigations of pure PIM-1 and PIM-1/CPSF-EtO mixed matrix membranes to establish a correlation between the molecular mobility and the gas transport properties. Using the time-lag method the gas permeability and the permselectivity were determined for N2, O2, CH4 and CO2 for samples with variation in filler content. A significant increase in the permeability of CH4 and CO2 (50 % increase compared to pure PIM-1) was observed for a concentration of 5 wt% of the nanofiller. Furthermore, the most pronounced change in the permselectivity was found for the gas pair CO2/N2 at a filler concentration of 7 wt%. KW - Polymers of Intrinsic Microporosity KW - Nanocomposites PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595031 DO - https://doi.org/10.1021/acs.macromol.3c02419 SN - 0024-9297 VL - 57 IS - 4 SP - 1829 EP - 1845 PB - ACS Publications AN - OPUS4-59503 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emamverdi, Farnaz A1 - Huang, J. A1 - Szymoniak, Paulina A1 - Bojdys, M. J. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Structure and molecular mobility of phosphinine-based covalent organic frameworks – glass transition of amorphous COFs N2 - Two-dimensional covalent organic frameworks (COFs) based on phosphinine and thiophene building blocks have been synthesized with two different side groups. The materials are denoted as CPSF-MeO and CPSF-EtO where CxxF correspond to the covalent framework, whereas P and S are related to heteroatoms phosphorous and sulfur. MeO and EtO indicate the substituents, i.e. methoxy and ethoxy. Their morphologies were studied by scanning electron microcopy and X-ray scattering. The absence of crystalline reflexes in the X-ray pattern reveal that both materials are amorphous and can be considered as glasses. Furthermore, N2 adsorption measurements indicate substantial Brunauer–Emmett–Teller (BET) surface area values pointing to the formation of three-dimensional pores by stacking of the aromatic 2D layer. An analysis of the porosity of both COFs showed a mean radius of the pores to be of ca. 4 nm, consistent with their chemical structure. The COFs form nanoparticles with a radius of around 100 nm. The thermal behavior of the COFs was further investigated by fast scanning calorimetry. These investigations showed that both COFs undergo a glass transition. The glass transition temperature of CPSF-EtO is found to be ca. 100 K higher than that for CPSF-MeO. This large difference in the glass transition is discussed to be due to a change in the interaction of the COF sheets induced by the longer ethoxy group. It might be assumed that for CPSF-EtO more individual COF sheets assemble to larger stacks than for CPSF-MeO. This agrees with the much larger surface area value found for CPSF-EtO compared to CPSF-MeO. To corroborate the results obtained be fast scanning calorimetry dielectric measurements were conducted which confirm the occurrence of a dynamic glass transition. The estimated temperature dependence of the relaxation rates of the dielectric relaxation and their absolute values agrees well with the data obtained by fast scanning calorimetry. Considering the fragility approach to the glass transition, it was further found that CPSF-MeO is a fragile glass former whereas CPSF-EtO behaves as a strong glass forming material. This difference in the fragility points also to distinct differences in the interaction between the 2D COF molecules in both materials. KW - Covalent Organic frameworks PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-596770 DO - https://doi.org/10.1039/d3ma01123b SP - 1 EP - 10 PB - Royal Society of Chemistry (RSC) AN - OPUS4-59677 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zorn, R. A1 - Lohstroh, W. A1 - Zamponi, M. A1 - Harrison, W. A1 - Budd, P. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Molecular mobility of a polymer of intrinsic microporosity revealed by quasielastic neutron scattering N2 - Quasielastic neutron scattering by employing a combination of time-of-flight and backscattering techniques is carried out to explore the molecular mobility of a polymer of intrinsic microporosity (PIM-1) at microscopic time scales in comparison with a high-performance polyimide. Molecular fluctuations can change the structure of the temporary network of micropores and open or close pathways for gas molecules. Therefore, the investigation might help to understand the selectivity of PIMs in gas separation processes. The performed neutron scattering experiments provide evidence for a low-temperature relaxation process, which was assigned to methyl group rotation. This methyl group rotation was analyzed in terms of jump diffusion in a three-fold potential. The analysis results in a fraction of methyl groups which are immobilized. For PIM-1 it was found that the fraction of immobilized methyl groups decreases with increasing temperature up to 350 K. At higher temperatures the number of immobilized methyl group increases gain due to an underlying relaxation process. This motional process on a somewhat larger length scale might lead to a reversible structural rearrangement which partially hinders the strongly localized methyl group rotation. In addition, it was found that the activation energy for the methyl group rotation for PIM-1 and the polyimide is significantly higher than for conventional polymers. KW - Polymer of intrinsic microporosity KW - Quasielastic neutron scattering PY - 2020 DO - https://doi.org/10.1021/acs.macromol.0c00963 SN - 0024-9297 SN - 1520-5835 VL - 53 IS - 15 SP - 6731 EP - 6739 PB - American Chemical Society CY - Washington, DC AN - OPUS4-51147 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kolmangadi, Mohamed Aejaz A1 - Szymoniak, Paulina A1 - Smales, Glen Jacob A1 - Alentiev, D. A1 - Bermeshev, M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Molecular Dynamics of Janus Polynorbornenes: Glass Transitions and Nanophase Separation N2 - For the first time, dielectric and calorimetric investigations of an homologous series of Janus polynorbornenes with rigid main backbones and flexible -Si(OR)3 side groups, of differing length alkyl chains (R = Propyl, Butyl, Hexyl, Octyl, Decyl) is reported. Generally, this class of polymers has some potential for applications in the field of gas separation membranes. Two dielectrically active processes are observed at low temperatures, denoted as β- and α- relaxation. The former can be assigned to localized fluctuations, whilst the latter is related to the glassy dynamics of the flexible -Si(OR)3 side groups, creating a nanophase separation in both the alkyl chain rich and backbone rich domains. This is confirmed through temperature modulated DSC measurements and X-ray scattering experiments. The glass transition temperatures of the backbone rich domains, which are beyond or near to their degradation temperatures in terms of conventional DSC, are determined for the first time using Fast Scanning Calorimetry employing both fast heating and cooling rates. This is complimented with scattering experiments that show how the size of the alkyl chain rich domains increases with chain length. Alongside these results, a significant conductivity contribution was observed for all poly(tricyclononenes) with -Si(OR)3 side groups, which is interpreted in terms of a percolation model. KW - Polynorbornenes KW - Broadband Dielectric Spectrscopy KW - Advanced calorimetry PY - 2020 DO - https://doi.org/10.1021/acs.macromol.0c01450 VL - 53 IS - 17 SP - 7410 EP - 7419 PB - ACS AN - OPUS4-51196 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schönhals, Andreas A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed Aejaz A1 - Böhning, Martin A1 - Zamponi, M. A1 - Frick, B. A1 - Appel, M. A1 - Günther, G. A1 - Russina, M. A1 - Alentiev, D. A1 - Bermeshev, M. A1 - Zorn, R. T1 - Microscopic dynamics of highly permeable super glassy polynorbornenes revealed by quasielastic neutron scattering N2 - The molecular dynamics of addition-type poly(tricyclononenes) with Si-substituted bulky side groups has been investigated by a combination of neutron time-of-flight and neutron backscattering spectroscopy methods on a time scale from 0.1 ps to ca. 3 ns. The investigated poly(tricyclononenes) PTCNSi1 and PTCNSi2g both bear a high microporosity which makes them promising candidates for active separation layers for gas separation membranes. At least for larger gas molecules it is assumed that the pathways for diffusion require an enlargement of pre-existing micropores in terms of an activated zone. A low temperature relaxation process was found for both polymers by the performed neutron scattering experiments. This process was assigned to the methyl group rotation. It was analysed in terms of a jump diffusion in a three-fold potential. The analysis of the dependence of the elastic incoherent structure factor on the scattering vector yields the number of methyl groups which might be immobilized. For PTCNSi1 (3 methyl groups in the monomeric unit) it was found that all methyl groups take part in the methyl group rotation whereas for PTCNSi2g (6 methyl groups in monomeric unit) a considerable number of methyl groups are blocked in their rotation. This immobilization of methyl groups is due to the sterically demanding arrangement of the methyl groups in PTCNSi2g. This conclusion is further supported by the result that the activation energy for the methyl group rotation is three times higher for PTCNSi2g than that of PTCNSi1. KW - Highly permeably polynorbornenes KW - Polymers of intrinsic microporosity KW - Gas separation membranes KW - Quasielastic neutron scattering PY - 2021 DO - https://doi.org/10.1016/j.memsci.2021.119972 SN - 0376-7388 VL - 642 PB - Elesevier B.V. AN - OPUS4-53508 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kolmangadi, Mohamed Aejaz A1 - Szymoniak, Paulina A1 - Smales, Glen Jacob A1 - Bermeshev, M. A1 - Schönhals, Andreas A1 - Böhning, Martin T1 - Molecular mobility of polynorbornenes with trimethylsiloxysilyl side groups: Influence of the polymerization mechanism N2 - We report dielectric and calorimetric studies on metathesis and addition-type polytricyclononenes, both based on the same monomer bearing three pendant OSiMe3 groups. For the addition-type polymer, dielectric spectroscopy reveals a β*-process related to the microporosity, whereas for its metathesis counterpart, the segmental dynamics manifests as an α-process related to a glass transition. Besides active dielectric processes, a significant conductivity contribution is detected for both samples which for the microporous additiontype polymer is three orders of magnitude greater than for the metathesis polymer. The broadband dielectric spectroscopy is complemented by detailed calorimetric investigations, comprising DSC, FSC, and TMDSC. The calorimetric methods detected the glass transition for the metathesis polymer in agreement with the observed dielectric α-process. Furthermore, the already reported gas transport properties for both polymers are compared, setting them in correlation with the observed molecular mobility and conductivity behavior. The discussed results reflect significant differences in molecular mobility of the two polymers affecting the appearance of microporosity which strongly determines the gas transport properties. KW - Microporous polymers KW - Molecular mobility KW - Electrical conductivity KW - Membrane polymers KW - Gas separation PY - 2022 DO - https://doi.org/10.22079/JMSR.2021.538060.1495 SN - 2476-5406 VL - 8 IS - 3 SP - 1 EP - 9 PB - Membrane Processes Research Laboratory (MPRL) CY - Tehran AN - OPUS4-54303 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zorn, R. A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed Aejaz A1 - Wolf, M. A1 - Alentiev, D. A1 - Bermeshev, M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Low frequency vibrational density of state of highly permeable super glassy polynorbornenes – The Boson peak N2 - Inelastic incoherent neutron time-of flight scattering was employed to measure the low frequency density of states for a series of addition polynorbornenes with bulky side groups. The rigid main chain in combination with the bulky side groups give rise to a microporosity of these polymers in the solid state. The microporosity characterized by the BET surfaces area varies systematically in the considered series. Such materials have some possible application as active separation layer in gas separation membranes. All investigated materials show excess contributions to the Debye type density of states characteristic for glasses known as Boson peak. The maximum position of the Boson peak shifts to lower frequency values with increasing microporosity. Data for PIM-1 and Matrimid included for comparison are in good agreement to this dependency. This result supports the sound wave interpretation of the Boson peak. KW - Polynorbornes KW - Neutron Scattering PY - 2020 DO - https://doi.org/10.1039/d0cp03360j SN - 1463-9076 VL - 22 IS - 33 SP - 18381 EP - 18387 PB - Royal Chemical Society AN - OPUS4-51165 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Physical investigations on Super glassy Polymers having possible applications in gas Separation Membranes N2 - The properties of polymers of intrinsic microporosity were investigated by fast scanning calorimetry, dielectric spectroscopy and neutron scattering T2 - University of Pennsylvania CY - Online meeting DA - 25.01.2021 KW - Polymer of intrisic microporosity PY - 2021 AN - OPUS4-52065 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Inelastic neutron scattering as a tool to investigate  polymers of intrinsic microporosity for green membrane processes and electronic applications N2 - Polymers with intrinsic microporosity are promising candidates for the active separation layer in green gas separation membranes and as active materials for electronic applicatons. Here, by means of inelastic neutron scattering, the vibrational density of states (VDOS) and the molecular mobility were investigated for PIM-1, the prototypical polymer with intrinsic microporosity. The results are compared to data measured for a more conventional high-performance polyimide used in gas separation membranes (Matrimid). The measured data show the characteristic low frequency excess contribution to the VDOS above the Debye sound wave level, generally known as the Boson peak in glass-forming materials. In comparison to the Boson peak of Matrimid, that of PIM-1 is shifted to lower frequencies. This shift is discussed considering the microporous, sponge-like structure of PIM-1 as providing a higher compressibility at the molecular scale than for conventional polymers. Elastic fixed window scans were measured on a neutron backscattering spectrometer to have an overview about the molecular dynamics at a time scale of ca. 1 ns. The temperature dependence of the estimated mean squared displacement shows a step-like increase in the temperature range from 100 K to 250 K indicating the onset of some molecular mobility. The nature of this motional process was analysed in detail by quasielastic neutron scattering combining Time-of-Flight and backscattering where the data are discussed with regard to both the q- and the temperature dependence. T2 - Symposium on Large Scale Facilities CY - Berlin, Germany DA - 09.03.2020 KW - Polymer membranen PY - 2020 AN - OPUS4-50546 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Böhning, Martin A1 - Goering, Harald A1 - Hao, Ning A1 - Schönhals, Andreas T1 - Polymer-based Nanocomposites - Particle Dispersion and Physical Properties T2 - Nanofair 2005 CY - Dresden, Germany DA - 2005-11-29 KW - Polymerbasierte Nanokomposite PY - 2005 SN - 3-18-091920-5 N1 - Serientitel: VDI-Berichte – Series title: VDI-Berichte IS - 1920 SP - 263 EP - 267 PB - VDI-Verl. CY - Düsseldorf AN - OPUS4-11589 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kamoun, E. A1 - Afifi, K. A1 - Szymoniak, Paulina A1 - Schönhals, Andreas A1 - Fahmy, Alaa T1 - Structure-property relationship of cross-linked chitosan-ethyl cellulose membranes N2 - Intensive research is focused on creating cost-effective, high-performance polyelectrolyte membranes (PEMs) for electrochemical devices designed to generate and/or store electrical energy. On the other hand, biopolymer materials have been utilized in a wide range of applications across medical and engineering fields, as well as in the textile and energy sectors. Therefore, in this study, chemically cross-linked chito-san/ethyl cellulose-citric acid (CS-EC-CA) membranes were prepared by a casting technique. The structure-property relationship of CS-EC/CA has been discussed based on the molar ratio of CS. The structural properties of the resultant membrane were characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy, thermal stability was assessed using thermogravimetric analysis. Moreover, the ion exchange capacity (IEC) and water uptake of the membrane were studied. FTIR analysis revealed a significant broadening of absorption peaks in the range of 3200–3500 cm-1 , corresponding to -OH groups, presence of CA. A new peak at 1725 cm-1 confirmed the formation of chemical linkages between CA and CS-EC. The results of the thermal analysis revealed that a thermally stable membrane was obtained when it was chemically cross-linked compared to non-cross-linked membranes. The IEC values of the modified membranes were enhanced significantly, increasing from 0.08 mmol/g for pure CS to 0.5 mmol/g for CS (50%) and 0.8 mmol/g for CS (50%) cross-linked withCA. Furthermore, the cross-linked membranes demonstrated the lowest water and ethanol uptake values, emphasizing their suitability for fuel cell applications. KW - Polyelectrolyte membranes PY - 2025 DO - https://doi.org/10.1063/5.0279022 SN - 1089-7666 VL - 37 IS - 8 SP - 1 EP - 11 PB - AIP Publishing AN - OPUS4-63890 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Böhning, Martin A1 - Tidjani, Adams A1 - Wald, Oliver A1 - Brzezinka, Klaus-Werner A1 - Turky, Gamal A1 - Goering, Harald A1 - Schartel, Bernhard A1 - Schönhals, Andreas T1 - Dielectric and gas transport properties of polypropylene-clay nanocomposites T2 - Frühjahrstagung des Arbeitskreises Festkörperphysik bei der DPG CY - Regensburg, Germany DA - 2002-03-11 PY - 2002 SN - 0420-0195 SN - 0372-5448 SN - 0343-9216 IS - CPP 5.4 SP - 425 CY - Bad Honnef AN - OPUS4-2036 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Molecular Mobility and Gas Transport of Polymer Based Nanocomposites T2 - International Seminar on Nanomaterials -Experiments and Simulations - Festseminar anläßlich des 80. Geburtstages von Prof. M. Kryszewski, ehemaliges Mitglied des Präsidium der Polnischen Akademie der Wissenschaften. Eingeladener Vortrag CY - Lodz, Poland DA - 2005-04-15 PY - 2005 AN - OPUS4-7311 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Conductivity and Gas Sorption Properties of Carbon Nanotube / Polycarbonate Nanocomposites T2 - Frühjahrstagung der Deutschen Physikalischen Gesellschaft (DPG) CY - Berlin, Germany DA - 2005-03-04 PY - 2005 AN - OPUS4-7129 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Konnertz, Nora A1 - Ding, Yi A1 - Harrison, W.J. A1 - Budd, P.M. A1 - Schönhals, Andreas A1 - Böhning, Martin T1 - Molecular mobility of the high performance membrane polymer PIM-1 as investigated by dielectric spectroscopy N2 - The increasing demand for energy efficient separation processes fosters the development of new high performance polymers as selective separation layers for membranes. PIM-1 is the archetypal representative of the class of polymers of intrinsic microporosity (PIM) which are considered most promising in this sector, especially for gas separations. Since their introduction, PIMs stimulated a vast amount of research in this field and meanwhile evolved to the state of the art in membrane technology for gas separation. The major obstacle for extending the practical membrane application is their strong tendency to physical aging. For the first time, investigations by broadband dielectric spectroscopy (BDS) addressing molecular dynamics and conductivity in PIM 1 are presented. As chain packing during film formation from the casting solution and physical aging are key factors determining the separation performance of PIMs as membrane materials, characterization of the molecular mobility in such materials as revealed by BDS will provide valuable information for further development and optimization. KW - PIM-1 KW - BDS broadband dielectric spectroscopy KW - Relaxation KW - Membrane PY - 2016 DO - https://doi.org/10.1021/acsmacrolett.6b00209 SN - 2161-1653 VL - 5 IS - 4 SP - 528 EP - 532 PB - ACS American Chemical Society CY - Washington, DC, USA AN - OPUS4-35798 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Konnertz, Nora A1 - Böhning, Martin A1 - Schönhals, Andreas A1 - Ding, Yi T1 - Molecular mobility and gas transport properties of PIM-1 and nano composites based on PIM-1 and phenethylPOSS N2 - Polymers with intrinsic microporosity are of highly interest in the field of gas separation membranes. Especially the first synthesized PIM-1 shows extraordinary permeabilities and selectivities. Unfortunately, PIM-1 tends to physical aging and loses its good properties. Physical aging is related to the molecular mobility of PIM-1 which was here investigated by broadband dielectric spectroscopy (BDS). Besides the studies on pure PIM-1 a polyhedral oligomeric silsesquioxane with phenethyl substituents (PhenethylPOSS) was used as nanofiller (0 - 40 wt-%) in the PIM-1 matrix to improve the gas transport properties and prevent physical aging. The molecular mobility of the solution casted nano composite films was analyzed by BDS as well. Furthermore, gas transport properties were determined with the time lag method (0 - 20 bar) in a temperature range of 35°C to 65°C with N2, O2, CH4 and CO2. T2 - 80. Jahrestagung der DPG und DPG-Frühjahrstagung CY - Regensburg, Germany DA - 06.03.2016 KW - PIM-1 PY - 2016 AN - OPUS4-35541 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zorn, R. A1 - Yin, Huajie A1 - Lohstroh, W. A1 - Harrison, W. A1 - Budd, P.M. A1 - Pauw, Brian Richard A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Anomalies in the low frequency vibrational density of states for a polymer with intrinsic microporosity - the Boson peak of PIM-1 N2 - Polymers with intrinsic microporosity are promising candidates for the active separation layer in gas separation membranes. Here, the vibrational density of states (VDOS) for PIM-1, the prototypical polymer with intrinsic microporosity, is investigated by means of inelastic neutron scattering. The results are compared to data measured for a more conventional high-performance polyimide used in gas separation membranes (Matrimid). The measured data show the characteristic low frequency excess contribution to VDOS above the Debye sound wave level, generally known as the Boson peak in glass-forming materials. In comparison to the Boson peak of Matrimid, that of PIM-1 is shifted to lower frequencies. This shift is discussed considering the microporous, sponge-like structure of PIM-1 as providing a higher compressibility at the molecular scale than for conventional polymers. For an annealed PIM-1 sample, the Boson peak shifts to higher frequencies in comparison to the un-annealed sample. These changes in the VDOS of the annealed PIM-1 sample are related to changes in the microporous structure as confirmed by X-ray scattering. KW - Polymers KW - Boson peak KW - Neutron scattering KW - Physical aging KW - Polymer of intrinsic microporosity PY - 2018 DO - https://doi.org/10.1039/C7CP07141H SN - 1463-9076 SN - 1463-9084 VL - 20 IS - 3 SP - 1355 EP - 1363 PB - The Royal Society of Chemistry AN - OPUS4-43808 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yin, Huajie A1 - Chua, Y. Z. A1 - Yang, B. A1 - Schick, C. A1 - Harrison, W. A1 - Budd, P. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - First clear cut experimental evidence for a glass transition in a polymer with intrinsic microporosity: PIM-1 N2 - Polymers with intrinsic microporosity (PIMs) represent a novel, innovative class of materials with great potential in various applications from high-performance gas separation membranes to electronic devices. Here for the first time, for PIM-1, as the archetypal PIM, fast scanning calorimetry provides definitive evidence for a glass transition (Tg=715 K, heating rate 3·10^4 K/s) by decoupling the time-scales responsible for glass transition and decomposition. As the rigid molecular structure of PIM-1 prevents any conformational changes, small-scale bend and flex fluctuations must be considered the origin of its glass transition. This result has strong implications for the fundamental understanding of the glass transition and for the physical aging of PIMs and other complex polymers, both topical problems of materials science. KW - Polymers with intrinsic microporosity KW - Fast Scanning Calorimetry PY - 2018 DO - https://doi.org/10.1021/acs.jpclett.8b00422 SN - 1948-7185 VL - 9 IS - 8 SP - 2003 EP - 2008 PB - ACS AN - OPUS4-44683 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Molecular mobility and physical aging of polymers with intrinsic microporosity as revealed by dielectric spectroscopy N2 - The dielectric properties of different polymers with intrinsic microporosity are investigated by braodband dielectric spectroscopy. The results are discussed with regard to the structure T2 - Spring Meeting of German Physical Society CY - Berlin, Germany DA - 12.03.2018 KW - Polymers with intrinsic microporosity KW - Gas separation membranes KW - Dielectric spectroscopy PY - 2018 AN - OPUS4-44490 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Famy, A. A1 - Agudo Jácome, Leonardo A1 - Schönhals, Andreas T1 - Effect of Silver Nanoparticles on the Dielectric Properties and the Homogeneity of Plasma Poly(acrylic acid) Thin Films N2 - For the first time, structure−electrochemical relationships of thin films of a plasma-polymerized acrylic acid/carbon dioxide AA/CO2 (75/25%) copolymer modified by implanted silver nanoparticles are discussed. The pulsed plasma polymerization of AA/CO2 was utilized and adjusted to obtain a maximal amount of COOH Groups forming an almost uncross-linked polymer structure. The prepared polymer layer is rinsed by a silver nitrate solution to impregnate Ag+ ions. This step is followed by its reduction of Ag+ with NaBH4 as a chemical route in comparison to the reduction by sunlight as an ecofriendly photoreduction method. The chemical composition and morphology of the topmost surface layer of the AA/CO2 polymer thin film were investigated by X-ray photoelectron spectroscopy and atomic force microscopy. Moreover, the molecular mobility, conductivity, and thermal stability of the polymer layer were analyzed using broadband dielectric spectroscopy. The dielectric properties of the AA/ CO2 polymer thin film were studied in the presence of Ag+ ions or Ag0. It was found that a cross-linked polymer layer with a smooth surface and high conductivity was obtained in the presence of Ag+/ Ag0. KW - Nanoparticles PY - 2020 DO - https://doi.org/10.1021/acs.jpcc.0c06712 SN - 1932-7447 VL - 124 IS - 41 SP - 22817 EP - 22826 PB - ACS AN - OPUS4-51468 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kolmangadi, Mohamed Aejaz A1 - Smales, Glen Jacob A1 - ZhuoQing, Li A1 - Yildirim, Arda A1 - Wuckert, E. A1 - Eutionnat, S. A1 - Demel, F. A1 - Huber, P A1 - Lasachat, S. A1 - Schönhals, Andreas T1 - Side Chain Length-Dependent Dynamics and Conductivity in Self-Assembled Ion N2 - We study the molecular mobility and electrical conductivity of a homologous series of linear shaped columnar ionic liquid crystals ILCn, (n = 8, 10, 12, 14, 16) using broadband dielectric spectroscopy (BDS), specific heat spectroscopy (SHS), and X-ray scattering. We aim to understand how the alkyl chain length influences the dynamics and electric conductivity in this system. Two dielectrically active relaxation modes are observed, the γ and the αcore process, that correspond to the localized fluctuations of the alkyl chains and cooperative motions of the aromatic core in the columns, respectively. Both the γ relaxation and the αcore process slow down with increasing alkyl chain length. SHS reveals one relaxation process, the αalkyl process that has a similar temperature dependence as that of the αcore process for ILC12, 14, and 16 but shifts to higher temperature for ILC8 and 10. For ILC12, 14, and 16, the absolute values of DC conductivity increase by 4 orders of magnitude at the transition from the plastic crystalline to hexagonal columnar phase. For ILC8 and 10, the DC conductivity behavior is similar to ionic liquids, where the conductivity is coupled with structural relaxation. Small-angle X-ray investigations reveal that both the intercolumnar distance and the disorder coherence length increase with alkyl chain length; conversely, the DC conductivity decreases monotonically. KW - Ionic Liquid Crystals PY - 2022 DO - https://doi.org/10.1021/acs.jpcc.2c03023 SN - 1932-7447 VL - 126 IS - 27 SP - 10995 EP - 11006 PB - ACS AN - OPUS4-55194 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nikitin, D. A1 - Biliak, K. A1 - Protsak, M. A1 - Adejube, B. A1 - Ali-Ogly, S. A1 - Škorvanková, K. A1 - Červenková, V. A1 - Katuta, R. A1 - Tosco, M. A1 - Hanuš, J. A1 - Černochová, Z. A1 - Černoch, P. A1 - Štěpánek, P. A1 - Boiko, O. A1 - Szymoniak, Paulina A1 - Schönhals, Andreas A1 - Faupel, F. A1 - Biedermann, H. A1 - Vahl, A. A1 - Choukourov, A. T1 - Unveiling the Fundamental Principles of Reconfigurable Resistance States in Silver/Poly(ethylene glycol) Nanofluids N2 - Developing novel memristive systems aims to implement key principles of biological neuron assemblies – plasticity, adaptivity, and self-organization – into artificial devices for parallel, energy-efficient computing. Solid-state memristive devices, such as crossbar arrays and percolated nanoparticle (NP) networks, already demonstrate these properties. However, closer similarity to neural networks is expected from liquid-state systems, including polymer melts, which remain largely unexplored. Here, the resistive switching in silver/poly(ethylene glycol) (Ag/PEG) nanofluids, prepared by depositing gas-aggregated Ag NPs into PEGs of varying molecular mass, is investigated. These systems form long-range conductive NP bridges with reconfigurable resistance states in response to an electric field. The zeta-potential of Ag NPs and molecular mobility of PEG determine the prevalence of low resistance (ohmic) state, high resistance states (poor conductance) or intermediate transition states governed by space-charge-limited conduction or electron tunneling. The occurrence of these states is given by the interparticle gaps, which are determined by the conformation of PEG molecules adsorbed on the NPs. It is presented, for the first time, an equivalent circuit model for the Ag/PEG system. These findings pave the way to adopt polymer melts as matrices for neuromorphic engineering and bio-inspired electronics. KW - Nanofluids PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-635351 DO - https://doi.org/10.1002/advs.202505103 VL - 12 SP - 1 EP - 14 PB - Wiley AN - OPUS4-63535 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Schönhals, Andreas A1 - Kremer, F. ED - Matyjaszewski, K. ED - Möller, M. T1 - Amorphous polymers N2 - The nature of the amorphous state in polymers is a classical topic in soft matter science with an immediate impact on modern technology. The chapter introduces the central concepts in this field and reviews a wealth of experimental information obtained by structural and dynamic techniques, such as neutron and X-ray scattering, broadband dielectric spectroscopy (BDS), nuclear magnetic resonance (NMR), and mechanical and specific heat spectroscopy, among others, covering dimensions between atomic (0.1 nm) to macroscopic (100 nm) length scales and timescales spanning more than 12 orders of magnitude, from picoseconds to seconds and longer. The theoretical models to describe the experimental findings are discussed in detail. Special attention is given to polymers having different architectures such as rings, stars, and block copolymers, and to the dynamics in nanometer thin layers. KW - Block copolymers KW - Chain dynamics KW - Dynamic glass transition KW - Glass transition temperature KW - Long-range order KW - Nanometric thin polymer layers KW - Ring polymers KW - Segmental dynamics KW - Short-range order KW - Star polymers PY - 2012 SN - 978-0-444-53349-4 DO - https://doi.org/10.1016/B978-0-444-53349-4.00010-8 VL - 1 IS - Chapter 1.08 SP - 201 EP - 226 PB - Elsevier CY - Amsterdam AN - OPUS4-26010 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -