Dispersion of cholesteric liquid crystals in side-chain polymer matrix

Cholesteric formulations (coco-cholesteryl esters:E7) were dispersed in com mercial polymethylmethacrylate (PMMA) and in laboratory synthesized side-ch ain polymers (SCP). The side-chain copolymers were obtained via the ring op ening reaction of a commercially available epon resin, ethyleneglycol digly cidyl ether, with the nematic 4-(omega-aminohexyloxy)-4'-cyanobiphenyl and the twisted nematic cholesteryl 4-aminobutyrate. Switching properties of th e resulting dispersions were evaluated. Cells using PMMA as matrix exhibite d distinguishable droplet with bipolar and twisted radial configuration. A maximum voltage of 60 volts was needed to transform a 70:30 by weight (LC:P MMA) composite into a transparent state. LC formulations dispersed in the S CP bearing cholesteryl and cyanobiphenyl pendant groups were found to exhib it fingerprint texture. Compared to the LC/PMMA composite, the LC/SCP dispe rsions required lower voltage for switching.