CONFORMATIONAL ORDER IN CRYSTALLINE STATES AND GELS OF ISOTACTIC, SYNDIOTACTIC AND ATACTIC POLYSTYRENES STUDIED BY VIBRATIONAL SPECTROSCOPY

被引:69
作者
NAKAOKI, T [1 ]
KOBAYASHI, M [1 ]
机构
[1] OSAKA UNIV,FAC SCI,DEPT MACROMOLEC SCI,TOYONAKA,OSAKA 560,JAPAN
关键词
D O I
10.1016/0022-2860(91)87144-7
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Stable conformations and their sequential order of isotatic (IPS), syndiotactic (SPS) and atactic polystyrenes (APS) in various aggregation states have been investigated by infrared (IR) spectroscopy, C-13 NMR and X-ray diffraction. It has been demonstrated that the partially ordered skeletal conformation existing in IPS/CS2 gels is of a (3/1) helix (TG) type having the pendant phenyl groups oriented in a disordered fashion, rather than the near-TT [(12/1) helix] form proposed previously for IPS/decalin gels. The process of conformational change during gelation of IPS/CS2 and APS/CS2 systems has been followed by IR spectroscopy, and it has been concluded that the construction of regular sequences of a particular conformation promotes the gelation of both crystallizable and non-crystalizable polystyrenes. As-cast film specimens prepared from a chloroform solution are found to be a crystalline polymer-solvent complex (the gamma phase) having a TTGG conformation. On heating, the gamma phase transforms to a beta phase at about 120-degrees-C, accompanied by removal of the solvent, while the TTGG conformation is retained. On further heating, the beta phase transforms to an alpha-1 or alpha-2 phase at about 200-degrees-C accompanied by a change in conformation from TTGG to TT. The process of conformational change (in both type and sequence) during these phase transformations has been clarified by IR spectroscopy.
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页码:315 / 331
页数:17
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