Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

    We have a manual that explains all the features 

Record number 342281
Title Multiple glass transitions in the plastic crystal phase of triphenylene derivates
Author(s) Yildirim, Z.; Wubbenhorst, M.; Mendes, E.; Picken, S.J.; Paraschiv, I.; Marcelis, A.T.M.; Zuilhof, H.; Sudhölter, E.J.R.
Source Journal of Non-Crystalline Solids 351 (2005)33-36. - ISSN 0022-3093 - p. 2622 - 2628.
Department(s) Laboratory for Organic Chemistry
Publication type Refereed Article in a scientific journal
Publication year 2005
Keyword(s) dielectric-relaxation spectroscopy - molecular-dynamics - liquid-crystal - nematic-columnar - separation - viscosity - polymers - mesogens - spectra - probes
Abstract The dynamics and phase behavior of the discotic liquid crystalline compound hexahexyloxytriphenylene (HAT6) and a derivative were studied by broad-band dielectric spectroscopy, differential scanning calorimetry, X-ray diffraction and optical microscopy. While the pristine compound HAT6 forms both a columnar mesophase (Colh) and a plastic crystal phase, no liquid crystallinity was observed for the highly asymmetric compound HAT6-C10Br. This paper focuses on the dielectric relaxations in the plastic crystal phase. For HAT6-C10Br, a `high temperature¿ glass transition, manifested by a Vogel¿Fulcher¿Tammann (VFT) type ¿2-process, was found at ¿31 °C that was assigned to the columnar glass transition in accordance with previous literature. The main result of our study is the observation of a second, low-temperature VFT process (¿1) for both compounds, which indicates co-operative liquid dynamics within the framework of the plastic crystal order at temperatures as low as ¿100 °C. Comparison of these fast dynamics with relaxation data from polyethylene and polymer series with long alkyl groups identifies this process as a `hindered¿ polyethylene-like dynamic glass transition that originates from the nanophase-separated, spatially confined fraction of aliphatic tails.
There are no comments yet. You can post the first one!
Post a comment
Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.