TY - JOUR A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed A. A1 - Böhning, Martin A1 - Frick, B. A1 - Apple, M. A1 - Mole, R. A. A1 - De Souza, N. R. A1 - Zorn, R. A1 - Schönhals, Andreas T1 - Confined Segmental Diffusion in Nanophase Separated Janus Polynorbornenes as Investigated by Quasielastic Neutron Scattering N2 - A combination of neutron time-of-flight and neutron backscattering spectroscopy was used to investigate the molecular dynamics of Janus polynorbornenes (Janus poly(tricyclononenes)) on a microscopic level. These Janus polynorbornenes, denoted as PTCNSiOR, have a semirigid backbone with −Si(OR)3 side groups attached to it. R represents the length of the alkyl side chain. Here side chain lengths of R = 3 (propyl) and R = 8 (octyl) were considered. It is worth mentioning that these polymers have some potential as active layers in gas separation membranes, especially for the separation of higher hydrocarbons. The combination of time-of-flight and backscattering will ensure a reasonably broad time window for analysis where the incoherent intermediate scattering function SInc(q,t) is considered. Previously, it was shown by X-ray investigations that the system undergoes a nanophase separation into alkyl side chain-rich domains surrounded by a backbone-rich matrix. For PTCNSiOPr (R = 3), the alkyl side-chain-rich domains are truly isolated in the backbone-rich matrix, whereas for PTCNSiOOc (R = 8) these domains percolate through the matrix. Further, it was also previously shown that the alkyl side-chain-rich domains undergo a glass transition. The advantage of neutron scattering experiments discussed here is that besides temporal also spatial information is obtained which will allow conclusions to be drawn about the type of molecular fluctuations. At the lowest measured temperature, the decay in Sinc(q,t) is due to the methyl group rotation. The methyl group dynamics is analyzed in terms of a modified jump-diffusion in a 3-fold potential and yields to a reasonable fraction of hydrogens which contribute to the methyl group rotation. At higher temperatures, the decay in SInc(q,t) is due to both the methyl group rotation and the segmental dynamics in the alkyl side-chain-rich domains. The segmental diffusion is modeled by a sublinear diffusion. For the analysis of the scattering function SInc(q,t) of PTCNSiOPr an elastic scattering due to the immobilized backbone-rich matrix must be taken into account. The analysis reveals that the segmental dynamics is confined by the finite size of alkyl chain-rich domains and that it is intrinsically heterogeneous in nature. Both effects are more pronounced for PTCNSiOPr in comparison to those of PTCNSiOOc. KW - Polynorbornene KW - Quasielastic Neutron Scattering PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608712 DO - https://doi.org/10.1021/acs.macromol.4c01045 SP - 1 EP - 14 PB - ACS Publications AN - OPUS4-60871 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed A. A1 - Böhning, Martin A1 - De Souza, N. R. A1 - Juranyi, F. A1 - Zorn, R. A1 - Schönhals, Andreas T1 - Inelastic and Quasielastic Neutron Scattering on Polynorbornenes with Bulky Carbocyclic Side groups N2 - This study investigates the molecular mobility and vibrational properties of polynorbornenes with bulky carbocyclic side groups using inelastic and quasielastic neutron scattering techniques. The polymers, synthesized via metathesis and addition polymerization, exhibit varying degrees of microporosity, which ignificantly influences their gas separation performance. By inelastic neutron scattering experiments, it could be shown that all considered polymers have excess contributions to the low frequency vibrational density of states known as the Boson peak. The maximum frequency of the Boson peak correlates to the microporosity of the polymers. This correlation supports the sound wave interpretation of the Boson peak, suggesting that the microporous structure enhances the compressibility of the material at a microscopic length scale. The molecular mobility, particularly the methyl group rotation, was characterized using elastic scans and quasielastic neutron scattering. The study revealed a temperature dependent relaxation process, with the onset of molecular fluctuations observed around 200 K for the polymer containing methyl groups. For the polymer having no methyl groups only elastic scattering is observed. The methyl group rotation was analyzed in terms of a jump diffusion in a threefold potential with three equivalent energy minima. This leads to an almost correct description of the q dependence of the elastic incoherent scattering function when the number of hydrogen nuclei undergoing the methyl group rotation is considered. It was further evidenced that the fraction of methyl undergoing the methyl group rotation increases with increasing temperature. KW - Polymers of Intrinsic Microporosity KW - Neutron scattering PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630297 DO - https://doi.org/10.1016/j.polymer.2025.128358 SN - 1873-2291 VL - 328 SP - 241 PB - Elsevier Ltd. AN - OPUS4-63029 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 - Malpass-Evans, R. A1 - McKeown, N. A1 - Jalarvo, N. A1 - Tyagi, M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Microscopic molecular mobility of high-performance polymers of intrinsic microporosity revealed by neutron scattering – bend fluctuations and signature of methyl group rotation N2 - Polymers of intrinsic microporosity exhibit a combination of high gas permeability and reasonable permselectivity, which makes them attractive candidates for gas separation membrane materials. The diffusional selective gas transport properties are connected to the molecular mobility of these polymers in the condensed state. Incoherent quasielastic neutron scattering was carried out on two polymers of intrinsic microporosity, PIM-EA-TB(CH3) and its demethylated counterpart PIM-EA-TB(H2), which have high Brunauer–Emmett–Teller surface area values of 1030 m2 g-1 and 836 m2 g-1, respectively. As these two polymers only differ in the presence of two methyl groups at the ethanoanthracene unit, the effect of methyl group rotation can be investigated solely. To cover a broad dynamic range, neutron time-of-flight was combined with neutron backscattering. The demethylated PIM-EA-TB(H2) exhibits a relaxation process with a weak intensity at short times. As the backbone is rigid and stiff this process was assigned to bendand-flex fluctuations. This process was also observed for the PIM-EA-TB(CH3). A further relaxation process is found for PIM-EA-TB(CH3), which is the methyl group rotation. It was analyzed by a jump-diffusion in a three-fold potential considering also the fact that only a fraction of the present hydrogens in PIM-EATB(CH3) participate in the methyl group rotation. This analysis can quantitatively describe the q dependence of the elastic incoherent structure factor. Furthermore, a relaxation time for the methyl group rotation can be extracted. A high activation energy of 35 kJ mol-1 was deduced. This high activation energy evidences a strong hindrance of the methyl group rotation in the bridged PIM-EA-TB(CH3) structure. KW - Polymers of Intrinsic Microporosity KW - Neutron Scattering PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604114 DO - https://doi.org/10.1039/d4sm00520a SP - 1 EP - 11 PB - RSC AN - OPUS4-60411 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 - Malpass-Evans, R. A1 - McKeown, N. A1 - Tyagi, M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Low frequency vibrations and diffusion in disordered polymers bearing an intrinsic microporosity as revealed by neutron scattering N2 - The microscopic diffusion and the low frequency density of states (VDOS) of PIM-EATB(CH3) are investigated by inelastic and quasi-elastic neutron scattering where also the demethylated counterpart of PIM-EA-TB(H2) is considered. These intrinsic microporous polymers are characterized by large BET surface area values of several hundred m2/g and pore sizes between 0.5 and 2 nm. Detailed comparison is made to the archetype of polymers of intrinsic microporosity, PIM-1, and polynorbornenes also bearing a microporosity. Due to the wavelength of neutrons, the diffusion and vibrations can be addressed on microscopic length and time scales. From the inelastic neutron scattering experiments the low frequency density of states (VDOS) is estimated which shows excess contributions to the Debye-type VDOS known as Boson peak. It was found that the maximum frequency of the Boson peak decreases with increasing microporosity characterized by the BET surface area. However, besides the BET surface area, additional factors such as the backbone stiffness govern the maximum frequency of the Boson peak. Further the mean squared displacement related to microscopic motions was estimated from elastic fixed window scans. At temperatures above 175 K, the mean squared displacement PIM-EA-TB(CH3) is higher than that for the demethylated counterpart PIM-EA-TB(H2). The additional contribution found for PIM-EATB(CH3) is ascribed to the rotation of the methyl group in this polymer because the only difference between the two structures is that PIM-EA-TB(CH3) has methyl groups where PIM-EA-TB(H2) has none. A detailed comparison of the molecular dynamics is also made to that of PIM-1 and the microporous polynorbornene PTCNSi1. The manuscript focuses on the importance of vibrations and the localized molecular mobility characterized by the microscopic diffusion on the gas Transport in polymeric separation membranes. In the frame of the random gate model localized fluctuations can open or close bottlenecks between pores to enable the diffusion of gas molecules. KW - Polymer of intrisic microporosity KW - Neutron scattering KW - Boson peak KW - Methyl group rotation PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538490 DO - https://doi.org/10.3390/cryst11121482 VL - 11 IS - 12 SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-53849 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emamverdi, Farnaz A1 - Yin, Huajie A1 - Smales, Glen Jacob A1 - Harrison, W. J. A1 - Budd, P. M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Polymers of intrinsic microporosity - Molecular mobility and physical aging revisited by dielectric spectroscopy and X‑ray scattering N2 - Polymers of intrinsic microporosity (PIMs) are promising candidates for the active layer in gas separation membranes due to their high permeability and reasonable permselectivity. These appealing properties originate from a microporous structure as a result of inefficient segment packing in the condensed state due to a combination of a ladder-like rigid backbone and sites of contortion. However, this class of polymers suffers from a significant decrease in the permeability with time due to physical aging, whereby typically, the permselectivity increases. The initial microporous structures approach a denser state via local rearrangements, leading to the reduction of the permeability. Hence, a detailed characterization of the molecular mobility in such materials can provide valuable information on physical aging. In this work, the dielectric behavior of PIM-1 films and their behavior upon heating (aging) were revisited by isothermal frequency scans during different heating/cooling cycles over a broad temperature range between 133 and 523 K (−140 to 250 °C). In addition, the obtained results were compared with data of samples that were annealed at ambient temperatures over different time scales. Multiple dielectric processes were observed: several relaxation processes due to local fluctuations and a Maxwell−Wagner−Sillars polarization effect related to the microporosity. The temperature dependence of the rates of all processes follows the Arrhenius law where the estimated activation energy depends on the nature of the process. The influence of the thermal history (aging) on the processes is discussed in detail. KW - Polymers of intrinsic microporosity PY - 2022 DO - https://doi.org/10.1021/acs.macromol.2c00934 VL - 55 SP - 7340 EP - 7350 PB - American Chemical Society CY - Washington, DC AN - OPUS4-55485 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed A. A1 - Juranyi, Fanni A1 - Böhning, Martin A1 - Zorn, Reiner A1 - Schönhals, Andreas T1 - Low-Frequency Vibrational Density of State of Janus-Polynorbornenes: The Dependence of the Boson Peak on the Nanophase-Separated Structure N2 - Inelastic incoherent neutron time-of-flight scattering was employed to investigate the low-frequency vibrational density of states (VDOSs) for a series of glassy Janus-poly(tricyclononenes), which consist of a rigid main chain and flexible alkyl side chains. Here, the length of the flexible side chains was systematically varied from propyl to octyl. Such materials have potential applications as active separation layers in gas separation membranes as a green future technology, especially for the separation of higher hydrocarbons. From the morphological point of view, the Janus polynorbornenes undergo a nanophase separation into alkyl side chain-rich nanodomains surrounded by a rigid polynorbornene matrix. Here, the influence of the nanophase-separated structure on the low-frequency VDOS is investigated from a fundamental point of view. The low-frequency VDOSs of these Janus polynorbornene show excess contributions to the Debye type VDOS known as the Boson peak (BP) for all side chain lengths. Due to the high incoherent scattering cross-section of hydrogen, most of the scattering comes from the alkyl side chain-rich domains. Compared to conventional glass-forming materials, in the considered Janus polynorbornenes, the BP has a much lower intensity and its frequency position is shifted to higher values. These experimental results are discussed in terms of the nanophase-separated structure where the alkyl chain-rich domains were constrained by the surrounding matrix dominated by the rigid backbone. With increasing alkyl chain length, the size of the alkyl chain-rich domains increases. The frequency position of the BP shifts linearly to lower frequencies with the size of these nanodomains estimated from X-ray measurements. The obtained results support the sound wave interpretation to the BP KW - Inelastic neutron scattering PY - 2023 DO - https://doi.org/10.1021/acs.macromol.3c00913 SN - 0024-9297 SP - 1 EP - 10 PB - ACS AN - OPUS4-57972 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 - 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 -