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@INPROCEEDINGS{Kolmangadi:1023010,
author = {Kolmangadi, Mohamed A. and Szymoniak, Paulina and Böhning,
Martin and Zorn, Reiner and Schönhals, Andreas},
title = {{L}ow frequency vibrational density of state of
{J}anus-polynorbornenes – {T}he dependence of the {B}oson
peak on the nanophase separated structure},
reportid = {FZJ-2024-01596},
year = {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},
month = {Aug},
date = {2023-08-12},
organization = {9th International Discussion Meeting
on Relaxation in Complex Systems,
Makuhari Messe (Japan), 12 Aug 2023 -
18 Aug 2023},
subtyp = {Invited},
cin = {JCNS-1 / IBI-8},
cid = {I:(DE-Juel1)JCNS-1-20110106 / I:(DE-Juel1)IBI-8-20200312},
pnm = {632 - Materials – Quantum, Complex and Functional
Materials (POF4-632) / 6G4 - Jülich Centre for Neutron
Research (JCNS) (FZJ) (POF4-6G4) / 5251 - Multilevel Brain
Organization and Variability (POF4-525) / 5241 - Molecular
Information Processing in Cellular Systems (POF4-524)},
pid = {G:(DE-HGF)POF4-632 / G:(DE-HGF)POF4-6G4 /
G:(DE-HGF)POF4-5251 / G:(DE-HGF)POF4-5241},
typ = {PUB:(DE-HGF)24},
url = {https://juser.fz-juelich.de/record/1023010},
}