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Proceedings Paper

Surface anchoring, polymer glass transition, and polymer-dispersed liquid crystal electro-optics
Author(s): John L. West; Keith Jewell; James J. Francl; Yimin Ji; Jack R. Kelly
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Paper Abstract

We studied the electro-optic properties as a function of temperature of a PDLC film composed of either E7 or E43 dispersed as droplets in a polyvinylformal (PVFM) matrix. The dissolved liquid crystal lowers the glass transition temperature, Tg, of the PVFM matrix to about 30 - 35 degree(s)C. The electro-optics of these PDLC films change abruptly at the polymer matrix Tg. In general the drive voltage decreases and the turn off time increases rapidly as the temperature is raised above Tg. Also, the shutter has essentially no hysteresis below, and significant hysteresis above Tg. These temperature effects are completely reversible. The rapid change in electro-optic properties cannot be entirely explained by changes in the polymer dielectric properties or droplet size and shape. We have therefore postulated that changes in the surface anchoring energy of the liquid crystal are primarily responsible for the abrupt changes in the electro-optic response at the matrix Tg.

Paper Details

Date Published: 15 June 1992
PDF: 5 pages
Proc. SPIE 1665, Liquid Crystal Materials, Devices, and Applications, (15 June 1992); doi: 10.1117/12.60372
Show Author Affiliations
John L. West, Kent State Univ. (United States)
Keith Jewell, Kent State Univ. (United States)
James J. Francl, Kent State Univ. (United States)
Yimin Ji, Kent State Univ. (United States)
Jack R. Kelly, Kent State Univ. (United States)

Published in SPIE Proceedings Vol. 1665:
Liquid Crystal Materials, Devices, and Applications
Paul S. Drzaic; Uzi Efron, Editor(s)

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