POLYMER NETWORK STRUCTURE AND ELECTROOPTIC PERFORMANCE OF POLYMER STABILIZED CHOLESTERIC TEXTURES - II - THE EFFECT OF UV CURING CONDITIONS

The effect of UV curing intensity and curing time on the electro-optic behaviour and network morphology of reverse mode polymer stabilized c holesteric textures (PSCTs) has been studied. Scanning electron microg raphs indicate that increasing the curing intensity generally results in a more open polymer network characterized by a larger average void size, while the morphology of the individual strands remains largely u nchanged. In addition, as the polymerization process proceeds, voids w ithin the network are observed to decrease in size. PSCTs with suffici ently large network voids exhibit a two-stage switching behaviour cons istent with a model in which the cholesteric liquid crystal is divided between two distinct environments-one in which the liquid crystal is strongly dominated by the polymer network, the other in which a bulk-l ike behaviour, comparable to the unstabilized cholesteric material, is observed.