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Structural and Dynamical Properties of n‐Alkane Molecules in Clathrate Phase of Syndiotactic Polystyrene
Author(s) -
Kaneko Fumitoshi,
Uda Yukihiro,
Kawaguchi Tatsuya,
Ute Koichi,
Yamamuro Osamu
Publication year - 2006
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200651017
Subject(s) - clathrate hydrate , alkane , heptane , octane , molecule , crystallography , polystyrene , hexane , chemistry , materials science , hydrocarbon , organic chemistry , hydrate , polymer
Syndiotactic polystyrene (sPS) forms a clathrate phase with a variety of compounds. Not only rigid molecules but also flexible molecules can be stored in the cavities of the clathrate phase. To clarify the adjustment mechanism of a flexible guest molecule to the sPS clathrate system, the host and guest structures were investigated by means of solid‐state 13 C NMR and Raman spectroscopy, and X‐ray diffractometry for the sPS clathrates with a series of n‐alkanes from n‐hexane to n‐decane. Although the 010 spacing of the host sPS lattice expanded slightly on going from n‐hexane to n‐heptane, it decreased markedly at n‐octane and then increased gradually with the chain length of guest n‐alkane. The conformational change of guest n‐alkane molecules was involved in this anomalous change in the 010 spacing. Majority of the n‐hexane and n‐heptane molecules took extended chain structures in the clathrates, whereas all longer n‐alkanes took bent chain structures. The mean‐square displacement of hydrogen atoms in the clathrates was estimated by quasielastic neutron scattering experiments. It was confirmed that the host lattice contraction suppressed thermal motion of the clathrate system.