Temperature stability of electro-optic properties of polymer dispersed liquid crystal with different crosslinking monomer in PN393 base pre-polymer

Abstract

The electro-optic properties of polymer-dispersed liquid crystals (PDLCs) fabricated by photo-induced phase separation have been investigated. A mixture of TL205 (80 wt%) liquid crystal and PN393 (20 wt%) pre-polymer having different crosslinking monomers was used for producing various PDLCs to compare its temperature stability. As a reference, a commercialized PN393 formulation was closely examined to compare the effects of replacing the crosslinker. The liquid crystal domain size varied from 3.5 mm to 10.3 µm depending on the crosslinker used. The larger domain size of PDLCs consisting of vinyl ether shows higher contrast ratio but faster response time and higher turnon voltage, which is contrary to the prediction. Acrylate-based PDLCs were found to be turned on, although abruptly increasing below 20 o C, and also showed heavy variation of other electro-optic over a wide operation temperature range. By substituting a vinyl-ether for the acrylate crosslinker, the temperature behavior was greatly improved.

Effects of Molar Ratios of Thiol-Ene Monomers on the Morphology and Electro-Optical Properties of Polymer Dispersed Liquid Crystal Films

“…One of the most important factors determining the electro-optical properties of PDLC is its morphology which is strongly affected by the prepolymer composition, solubility between the LC and prepolymer, the polymerization kinetics, and the phase separation mechanism [17][18][19][20][21][22][23][24][25][26][27]. For the PDLC films prepared using thiolene systems, the droplet morphology and structural parameters such as droplet size, shape, distribution and density can be varied with the chemical characteristics of the prepolymer and polymerization kinetics.…”