Thermotropic liquid crystalline polymers—20. Study by i.r.-dichroism spectroscopy of an oriented state of comb-like liquid-crystalline polymers with cyanobiphenyl mesogenic groups

✍ Scribed by Z.A. Roganova; A.L. Smolyansky; S.G. Kostromin; V.P. Shibaev

• Publisher: Elsevier Science
• Year: 1985
• Tongue: English
• Weight: 441 KB
• Volume: 21
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(85)90099-0

✦ Synopsis

The peculiarities of orientation of liquid crystalline (LC) comb-like polymers by action of a shear stress were studied by i.r.-spectroscopy. It has been shown that the type of orientation depends on the average degree of polymerization (/r). The long axes of mesogenic groups are oriented along the shear direction at Pw < 100 and they are normal to this orientation at P, > 100. The degree of orientation of mesogenic group (S*) and spacer (S*) was estimated over a wide temperature range. In the LC state of polymers, the S* values (0.4-0.5) exceed the S~ values (0.1-0.3). To explain this difference, the conformation state of the spacer was considered. For polyacrylate samples with 11 methylene groups in the spacer, the content of gauche isomers in the SA-mesophase is around 25%. At the SA-S c transition, the content gauche of isomers is decreased.