Optical anisotropy and orientational elastic constants of polymer high-temperature and re-entrant nematics

Alexander P. Filippov; L. N. Andreeva; E. B. Barmatov; Valery P. Shibaev

doi:10.1117/12.300004

1 February 1998 Optical anisotropy and orientational elastic constants of polymer high-temperature and re-entrant nematics

Alexander P. Filippov, L. N. Andreeva, E. B. Barmatov, Valery P. Shibaev

Author Affiliations +

Proceedings Volume 3318, Liquid Crystals: Physics, Technology, and Applications; (1998) https://doi.org/10.1117/12.300004
Event: Liquid Crystals, 1997, Zakopane, Poland

Abstract

Orientational elastic deformations of polymer high temperature and reentrant nematics in a magnetic field were studied using the method of Freedericksz transitions. Experiments were performed on a series of fractions of a comb-like polymer. The temperature dependences of orientational elastic constants K₁ and K₃ in the nematic and reentrant nematic phases and birefringence (Delta) n and, correspondingly, the orientational order parameters S do not undergo a pronounced jump. The study of mechanical equilibrium characteristics did not reveal any differences in the behavior of high temperature and reentrant nematic phases of the polymer. For the lowest molecular weight fraction, an anomalous 'bell-shaped' temperature dependence of the bend constant K₃ was found. This dependence can be explained by the formation of small domains with smectic ordering in the nematic phase. In the molecular weight range investigated, both optical anisotropy and equilibrium mechanical characteristics are independent of M.

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Alexander P. Filippov, L. N. Andreeva, E. B. Barmatov, and Valery P. Shibaev "Optical anisotropy and orientational elastic constants of polymer high-temperature and re-entrant nematics", Proc. SPIE 3318, Liquid Crystals: Physics, Technology, and Applications, (1 February 1998); https://doi.org/10.1117/12.300004

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