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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},
}