A dynamic study of dipole alignment in a main-chain liquid-crystal polymer exposed to an electric field revealed some fundamental properties of these macromolecules. The polymer studied was the polycondensate of 40 mol % polyethylene terephthalate) and 60 mol % p-acetoxybenzoic acid. Spectroscopic analysis of attenuated infrared reflections during application of an electric field allowed us to measure the spatial alignment of ester dipole moments. When poling occurs before or during the solid to liquid-crystal transformation, one observes a relatively fast dielectric alignment which remains stable in the liquid-crystal phase. When the liquid crystal is solidified under the field the extent of polar alignment for moments nearly orthogonal to the backbone could lie in the range of 4-10%. This range suggests that interchain dipolar coupling is an important phenomenon in these polymers. On this basis one may also expect that localized ferroelectric ordering enhances cooperative behavior during the transition from "poled" solid to liquid crystal. The observed phenomena could be useful in the formation of polymeric solids with electrical or nonlinear optical properties.
|Number of pages||7|
|Publication status||Published - 1987|
ASJC Scopus subject areas
- Materials Chemistry