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| Home > Publications database > Low frequency vibrational density of state of Janus-polynorbornenes – The dependence of the Boson peak on the nanophase separated structure |
| Home > Publications database > Low frequency vibrational density of state of Janus-polynorbornenes – The dependence of the Boson peak on the nanophase separated structure |
| Poster (Invited) | FZJ-2024-01596 |
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2023
Abstract: The low frequency density of states (VDOS) for a homologous series of glassy Janus- poly(tricyclononenes) with a rigid backbone and flexible alkyl side chains, PTCNSiOR (R = propyl – octyl), was studied using inelastic incoherent neutron time-of flight scattering where the spectrometer FOCUS (Paul Scherrer Institut, Switzerland) was employed. From the morphological point of view the Janus-polynorbornenes phase separate into alkyl chain-rich nanodomains surrounded by a rigid polynorbornene matrix.1 These materials have potential application as active separation layer in green gas separation membranes where the gas transport occurs through the nanophase separated flexible alkyl domains.For the whole series, the low frequency vibrational density of states (VDOS) shows excess contributions to the Debye type VDOS known as Boson peak (BP). The scattering contribution is dominated by the alkyl chain rich domains due to the high scattering cross-section of hydrogen nuclei. Compared to conventional glassy-forming materials, the Boson peak of Janus polynorbornenes has a much lower intensity and is shifted to higher frequencies. The Boson peak shifts linearly to lower frequencies with increasing size of the alkyl chain-rich domains. The data for the Janus- poly(tricyclononenes) are compared to that obtained for a homologous series of a columnar liquid crystal based on hexakis(n-alkyloxy)triphenylene (HATn).2 The investigation provides evidence that the BP is due to collective excitations like sound waves/phonons.REFERENCES1. Kolmangadi, M.; Szymoniak, P.; Smales, G. J.; Böhning, M.; Schönhals, A. et al. Macromolecules 53 (2020) 7410 2. Krause, C.; Zorn, R.: Emmerling, F.; Falkenhagen, J.; Frick, B.; Huber, P.; Schönhals, A. Phys. Chem. Chem. Phys. 16 (2014) 7324
Keyword(s): Energy (1st) ; Soft Condensed Matter (2nd)
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