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Please use this identifier to cite or link to this item: http://hdl.handle.net/10119/12864

Title: Dynamics of a Probe Molecule Dissolved in Several Polymer Matrices with Different Side-Chain Structures: Determination of Correlation Length Relevant to Glass Transition
Authors: Nobukawa, Shogo
Urakawa, Osamu
Shikata, Toshiyuki
Inoue, Tadashi
Issue Date: 2013-03-15
Publisher: American Chemical Society
Magazine name: Macromolecules
Volume: 46
Number: 6
Start page: 2206
End page: 2215
DOI: 10.1021/ma302567j
Abstract: Dynamics of 4-pentyl-4’-cyanobiphenyl (5CB) dissolved in several polymers at concentrations of 3 - 7 wt% was examined by dielectric relaxation measurement. Glassy (segmental) mode of the matrix polymer was also investigated by viscoelastic measurements for the same samples. Polystyrene (PS), poly(4-methylstyrene) (P4MS), and poly(4-tert-butylstyrene) (PtBS) were used as host polymers considering that they have the same backbone structure but different side-chain bulkiness. Two dielectric relaxation modes (slow and fast modes) of 5CB component appeared in all the mixtures and the relative intensity of the fast mode increased in the order of PS < P4MS < PtBS, corresponding to the order of the side-chain bulkiness and main chain stiffness. The effects of such chemical structure differences on the two relaxation modes, particularly their temperature dependence were examined in detail. Comparison of relaxation times for the fast mode and the segmental dynamics of the matrix polymer suggests that the fast mode was attributed to the restricted orientational fluctuation, which includes precession motion around the long axis, of 5CB molecule in a confined space formed by slow polymer chains. The dielectric intensity of the fast mode increased with increasing side-chain bulkiness of polymers. This means that the larger side-chain decreases the spatial restriction for the movement of guest 5CB molecules in the glassy state. The slow mode was attributed to the rotational motion of 5CB molecule nearly cooperative with the segmental motion of matrix polymer. The relaxation times of dielectric slow mode and viscoelastic glass mode were compared. Temperature dependence of the slow mode was slightly different from that of the segmental motion of polymer corresponding to the glass mode. From the difference between these relaxation times, the correlation length relevant to the glass mode was determined as functions of temperature for the three polymers.
Rights: Shogo Nobukawa, Osamu Urakawa, Toshiyuki Shikata, and Tadashi Inoue, Macromolecules, 2013, 46(6), pp.2206-2215. This document is the unedited author's version of a Submitted Work that was subsequently accepted for publication in Macromolecules, copyright (c) American Chemical Society after peer review. To access the final edited and published work, see http://dx.doi.org/10.1021/ma302567j
URI: http://hdl.handle.net/10119/12864
Material Type: author
Appears in Collections:c10-1. 雑誌掲載論文 (Journal Articles)

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