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Proceedings Paper

Features of critical behavior of bend elastic constants of polymer liquid crystal near nematic-smectic A phase transition point
Author(s): Alexander P. Filippov; Vjacheslav V. Suev
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Paper Abstract

The temperature dependences of the elastic splay K1 and bend K3 constants and birefringence (Delta) n of a comblike combined side- and main-chain polymer near nematic (N)--smectic A (SA) phase transition were investigated using the method of the Freedericksz threshold transitions. Experiments were performed on a series of fractions in the range of molecular weight from 900 to 10200. The splay constant K1 and birefringence (Delta) n have practically normal `nematic' temperature dependence in the investigated temperature range. For some fractions near the N$ARLRSA transition, the bend constant K3 exhibits a rapid increase with decreasing temperature, which is explained by the fluctuations of smectic order in the nematic phase. For high molecular weight fractions, the fluctuation-dependent part of K3 varies as (T - TN-SmA)-(rho ) according to theoretical predictions. Hence, the values of critical exponent (rho) are very large (1.1 - 1.4). For low molecular weight fractions, no agreement is observed between the results obtained and theoretical predictions. The features of critical behavior of bend elastic constants of liquid crystal investigated may be explained by the molecular weight polydispersity of polymer fractions.

Paper Details

Date Published: 12 May 2000
PDF: 6 pages
Proc. SPIE 4147, Liquid Crystals: Chemistry, Physics, and Applications, (12 May 2000); doi: 10.1117/12.385713
Show Author Affiliations
Alexander P. Filippov, Institute of Macromolecular Compounds (Russia)
Vjacheslav V. Suev, Institute of Macromolecular Compounds (Russia)


Published in SPIE Proceedings Vol. 4147:
Liquid Crystals: Chemistry, Physics, and Applications
Stanislaw J. Klosowicz; Jolanta Rutkowska; Jerzy Zielinski; Jozef Zmija, Editor(s)

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