DEPENDENCE OF THE MORPHOLOGY OF POLYMER-DISPERSED LIQUID-CRYSTALS ON THE UV POLYMERIZATION PROCESS

Using confocal microscopy, we have studied the morphology of polymer d ispersed liquid crystals (PDLC) as a function of polymer/liquid crysta l composition, polymer cure temperature, and ultraviolet (UV) curing p ower and determined how this morphology affects the electro-optical pr operties. The PDLC morphology consists of a spongelike texture where s pherically shaped liquid crystalline domains are dispersed in a polyme r matrix, These domains grow as the fraction of Liquid crystal increas es and as the UV curing power decreases,We observe no significant chan ges in domain size with changes in the curing temperature. Instead, hi gh-temperature cures result in coalescence and the formation of ellipt ical-shaped liquid crystal domains. The temperature al which this coal escence starts to be observed marks a threshold temperature T-th, abov e which the switching properties are strongly dependent on morphology. Below T-th the switching properties are largely independent of morpho logy. (C) 1997 American Institute of Physics.