TY - CONF A1 - Schönhals, Andreas T1 - Polymers confined to nanoporous glasses investigated by quasielastic and inelastic neutron scattering T2 - Workshop Confit 2006 CY - Grenoble, France DA - 2006-03-23 PY - 2006 AN - OPUS4-12000 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Molecular fluctuations of 4-n-octyl-4'cyanobiphenyl confined to nanoporous SBA-type molecular sieves with different filling degrees T2 - Workshop Confit 2006 CY - Grenoble, France DA - 2006-03-23 PY - 2006 AN - OPUS4-12005 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Neutron spectroscopy on polymers confined to nanoporous glasses T2 - Frühjahrstagung der Deutschen Physikalischen Gesellschaft CY - Dresden, Germany DA - 2006-03-21 PY - 2006 AN - OPUS4-12032 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Frunza, Ligia A1 - Kosslick, H. A1 - Frunza, Stefan A1 - Schönhals, Andreas T1 - Molecular dynamics of 4-n-octyl-4'-cyanobiphenyl in partially filled nanoporous SBA-type molecular sieves N2 - The molecular dynamics of 4-n-octyl-4'-cyanobiphenyl (8CB) confined to the nanopores of new SBA-type molecular sieves was investigated in a wide temperature range using broadband dielectric spectroscopy (10-2–109 Hz). One molecular sieve has a hexagonal structure of the pores while the other is a cellular nanoporous material. To explore the extent of surface interaction effects a high and a low filling degree were considered. For the molecular sieves with a high filling degree two relaxation regions were observed: a bulk-like relaxation process related to molecules, which behave as mesophase, located in the centre of the pores. The second relaxation process has a much lower relaxation rate than the former and is assigned to molecules located in a surface layer. The temperature dependence of its relaxation rates follows the Vogel–Fulcher–Tammann law, characteristic for glassy dynamics. For samples with a low filling degree only one relaxation process due to the surface layer was observed. Moreover, especially at the temperatures lower than the melting point of bulk 8CB, its relaxation rate is situated between the characteristic frequencies of the two relaxation processes observed for the pores with a high filling degree. This behaviour gives a measure of the extension of the influence of the wall on the neighbouring 8CB molecules. In addition, the differences revealed by the molecule dynamics inside the two types of nanoporous materials are related to both surface interactions and geometrical constraints. KW - Confined liquid crystals KW - Molecular sieves KW - Dielectric measurements KW - Relaxation processes KW - Glassy dynamics PY - 2006 DO - https://doi.org/10.1016/j.micromeso.2005.10.025 SN - 1387-1811 SN - 1873-3093 VL - 90 IS - 1-3 SP - 259 EP - 270 PB - Elsevier CY - Amsterdam AN - OPUS4-12118 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas A1 - Goering, Harald A1 - Schick, C. T1 - Poly(methyl phenyl siloxane) in Random Nanoporous Glasses - Comparison of coated and uncoated confining surfaces T2 - Poly(methyl phenyl siloxane) in Random Nanoporous Glasses: Comparison of coated and uncoated confining surfaces CY - Boston, MA, USA DA - 2006-11-28 PY - 2006 VL - 899E SP - 0899-N09-05.1-0899-N09-05.6 CY - Boston AN - OPUS4-12214 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Structure property relationships of different polymer based nanocomposites as investigated by dieletric spectroscopy and gas transport measurements T2 - 2nd International Symposium on Nanostructured and Functional Polymer-based Materials and Nanocomposites (NANOFUN-POLY) CY - Lyon, France DA - 2006-05-29 PY - 2006 AN - OPUS4-12393 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Polymer based nanocomposites as investigated by dielectric spectroscopy, gas transport measurements and related techniques T2 - NoE Nanofun Polymer, 6. FP der EU CY - Poznan, Poland DA - 2006-09-01 PY - 2006 AN - OPUS4-12625 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Polymers confined to Nanoporous Glasses T2 - Vortrag am National Research Center, Kairo CY - Cairo, Egypt DA - 2005-10-16 PY - 2005 AN - OPUS4-11669 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Polymers in Random Nanoporous Glasses Investigated by Dielectric, Thermal and Neutron Spectroscopy T2 - Herbst Meeting der Amerikanischen Gesellschaft für Materialforschung, 01.12. CY - Boston, MA, USA DA - 2005-11-27 PY - 2005 AN - OPUS4-11708 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Molecules in nanometre confinement investigated by dieletric spectroscopy and related techniques T2 - 4. Conference of the International Dieletric Society CY - Poznan, Poland DA - 2006-09-03 PY - 2006 AN - OPUS4-13042 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schick, C. A1 - Sukhorukov, D. A1 - Schönhals, Andreas T1 - Comparison of the Molecular Dynamics of a Liquid Crystalline Side Group Polymer Revealed from Temperature Modulated DSC and Dielectric Experiments in the Glass Transition Region N2 - Temperature modulated DSC (TMDSC) in the frequency range from 10-3 Hz to 3.4 10-2 Hz and dielectric spectroscopy in the frequency range from 10-2 Hz to 106 Hz is employed to analyze the temperature dependence of the relaxation rates of the - and of the -relaxation of a liquid crystalline polymethacrylate having a derivative of (p-alkoxy-phenyl)-benzoate as mesogenic unit in the side group. Especially the molecular assignment of the -relaxation was discussed controversial in the literature up to now. By applying a temperature derivative method it was found that the temperature dependencies of the relaxation rates of the dielectric -relaxation and of the dynamic glass transition measured by TMDSC can be described by Vogel/Fulcher/Tammann laws with the same Vogel temperature. Therefore it is argued that the dielectric -relaxation of liquid crystalline polymers is rather due to the dynamic glass transition related to the segmental dynamics of the backbone than to the transverse dipole component of the mesogenic unit. PY - 2001 DO - https://doi.org/10.1002/1521-3935(20010501)202:8<1398::AID-MACP1398>3.0.CO;2-C SN - 1022-1352 SN - 1521-3935 VL - 202 IS - 8 SP - 1398 EP - 1404 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-13693 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Polymers confined to nanoporous glasses investigated by quasielastic and inelastic neutron scattering T2 - Soft Matter User Meeting CY - Grenoble, France DA - 2006-11-22 PY - 2006 AN - OPUS4-13881 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Polymers in nanoconfinements investigated by various spectroscopic methods T2 - Department of Physics and Astronomy, Universität Leuven CY - Leuven, Belgium DA - 2006-11-30 PY - 2006 AN - OPUS4-14203 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Molecular Dynamics of polar molecules in nanometre confinement T2 - Vortrag an der Universität Lissabon, Fakultät für Chemie CY - Lisbon, Portugal DA - 2007-01-17 PY - 2007 AN - OPUS4-14503 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Neutron Spectroscopy on nano-confined polymers in comparison with dielectric and thermal results T2 - Jahrestagung der Deutschen Physikalischen Gesellschaft, AK Chemische Physik/Polymerphysik CY - Regensburg, Germany DA - 2007-03-26 PY - 2007 AN - OPUS4-14566 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schönhals, Andreas A1 - Goering, Harald A1 - Schick, C. A1 - Frick, B. A1 - Mayorova, M. T1 - Segmental dynamics of poly(methyl phenyl siloxane) confined to nanoporous glasses N2 - The effect of a nanometer confinement on the molecular dynamics of poly(methyl phenyl siloxane) (PMPS) was studied by dielectric spectroscopy (DS), temperature modulated DSC (TMDSC) and neutron scattering (NS). Nanoporous glasses with pore sizes of 2.5–20 nm have been used. DS and TMDSC experiments show that for PMPS in 7.5 nm pores the molecular dynamics is faster than in the bulk which originates from an inherent length scale of the underlying molecular motions. For high temperatures the temperature dependence of the relaxation rates for confined PMPS crosses that of the bulk state. Besides finite states effects also the thermodynamic state of nano-confined PMPS is different from that of the bulk. At a pore size of 5 nm the temperature dependence of the relaxation times changes from a Vogel/Fulcher/Tammann like to an Arrhenius behavior where the activation energy depends on pore size. This is in agreement with the results obtained by NS. The increment of the specific heat capacity at the glass transition depends strongly on pore size and vanishes at a finite length scale between 3 and 5 nm which can be regarded as minimal length scale for glass transition to appear in PMPS. PY - 2007 SN - 1951-6355 SN - 1951-6401 VL - 141 IS - 1 SP - 255 EP - 259 PB - Springer CY - Berlin AN - OPUS4-14602 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Dielectric and neutron spectroscopy on nano-confined liquid crystals T2 - Jahrestagung der Deutschen Physikalischen Gesellschaft, AK Chemische Physik/Polymerphysik CY - Regensburg, Germany DA - 2007-03-26 PY - 2007 AN - OPUS4-14590 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Molecular dynamics in glass-forming liquid crystal as studied by broadband dielectric and thermal spectroscopy T2 - Jahrestagung der Deutschen Physikalischen Gesellschaft, AK Chemische Physik/Polymerphysik CY - Regensburg, Germany DA - 2007-03-26 PY - 2007 AN - OPUS4-14592 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hao, Ning A1 - Böhning, Martin A1 - Goering, Harald A1 - Schönhals, Andreas T1 - Nanocomposites of Polyhedral Oligomeric Phenethylsilsesquioxanes and Poly(bisphenol A carbonate) as Investigated by Dielectric Spectroscopy N2 - Nanocomposites were prepared by solution blending of polyhedral oligomeric silsesquioxane with phenethyl substituents (PhenethylPOSS) into poly(bisphenol A carbonate) (PBAC). The nanocomposites were investigated by dielectric spectroscopy, differential scanning calorimetry (DSC) and density measurements. PhenethylPOSS shows one relaxation process, the α-relaxation, confirmed by DSC investigations. PBAC shows a β-relaxation at lower and an α-relaxation at higher temperatures. With increasing PhenethylPOSS content the α-relaxation of the composites shifts to lower temperatures. Thus, incorporation of PhenethylPOSS leads to a plasticization of PBAC due to a decrease of the packing density which is rationalized by density measurements. For higher concentrations of PhenethylPOSS (>10 wt %) the α-relaxation of the polycarbonate matrix splits into two peaks. Moreover, close to the α-relaxation of PhenethylPOSS a third process is observed. These results indicate a phase separation into a PBAC matrix with a few percents of molecularly solved POSS and POSS-rich domains. These POSS-rich domains are surrounded by an interfacial layer of PBAC having a higher concentration of POSS than the matrix. A phase diagram is deduced providing a miscibility criterion. For the phase separated nanocomposites an interfacial polarization phenomena is observed. Using a simplified model the time constant of this process is correlated with the size of the PhenethylPOSS-rich domains and theire increasing size with the increase of the concentration of POSS. KW - Polyhedral oligomeric silsesquioxane (POSS) KW - Polymer-based nanocomposites KW - Broadband dielectric spectroscopy KW - Interfacial polarisation PY - 2007 SN - 0024-9297 SN - 1520-5835 VL - 40 IS - 8 SP - 2955 EP - 2964 PB - American Chemical Society CY - Washington, DC AN - OPUS4-14768 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brás, A. R. A1 - Dionísio, M. A1 - Huth, H. A1 - Schick, C. A1 - Schönhals, Andreas T1 - Origin of glassy dynamics in a liquid crystal studied by broadband dielectric and specific heat spectroscopy N2 - A combination of broadband dielectric (10-2 Hz–109 Hz) and specific heat (10-3 Hz–2×103 Hz) spectroscopy is employed to study the molecular dynamics of the glass-forming nematic liquid crystal E7 in a wide temperature range. In the region of the nematic phase the dielectric spectra show two relaxation processes which are expected theoretically: The δ relaxation which corresponds to rotational fluctuations of the molecules around its short axis and the tumbling mode at higher frequencies than the former one. For both processes the temperature dependence of the relaxation rates follows the Vogel-Fulcher-Tammann formula which is characteristic for glassy dynamics. By applying a detailed data analysis, it is shown that close to the glass transition the tumbling mode has a much steeper temperature dependence than the δ process. The former has a Vogel temperature which is by 30 K higher than that of the δ relaxation. Specific heat spectroscopy gives one relaxation process in its temperature and frequency dependence which has to be assigned to the α relaxation (dynamic glass transition). The unique and detailed comparison of the temperature dependence of the dielectric and the thermal relaxation rates delivers unambiguously that the dielectric tumbling mode has to be related to the dynamic glass transition. PY - 2007 DO - https://doi.org/10.1103/PhysRevE.75.061708 SN - 1539-3755 SN - 1063-651X VL - 75 IS - 6 SP - 061708-1-061708-8 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-15041 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Structure property relationships of polymeric nanocomposites based on polyhedral oligomeric silsesquioxanes T2 - Meeting American Chemical Society CY - Boston, MA, USA DA - 2007-07-19 PY - 2007 AN - OPUS4-15457 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hao, Ning A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Gas Transport Properties of Polymeric Nanocomposites Based on Polyhedral Oligomeric Silsesquioxanes PY - 2007 SN - 0743-0515 VL - 97 SP - 444 EP - 445 PB - Division of Polymeric Materials Science and Engineering, American Chemical Society CY - Washington, DC AN - OPUS4-15846 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schönhals, Andreas A1 - Schick, C. A1 - Huth, H. A1 - Frick, B. A1 - Mayorova, M. A1 - Zorn, R. T1 - Molecular dynamics in glass-forming poly(phenyl methyl siloxane) as investigated by broadband thermal, dielectric and neutron spectroscopy KW - Neutron diffraction/scattering KW - Dielectric properties KW - Relaxation KW - Electric modulus KW - Glass transition PY - 2007 SN - 0022-3093 VL - 353 IS - 41-43 SP - 3853 EP - 3861 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-15898 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas T1 - Molecular mobility poly(phenyl methyl siloxane) invesstigated by thermal, dielectric and neutron spectroscopy T2 - Meeting of the American Chemical Society, PMSE CY - Boston, MA, USA DA - 2007-08-19 PY - 2007 AN - OPUS4-15463 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -