Electro-Optic and Thermo-Optic Properties of Phase Separated Polymer Dispersed Liquid Crystal Films

Abstract

Polymer dispersed liquid crystal (PDLC) and guest host polymer dispersed liquid crystal (GHPDLC) films were prepared by phase separated polymerization induced phase separation (PIPS) technique. Micro-texture studies shows that the liquid crystal droplets of varying size (∼ 5–40 μm) consists mainly of bipolar configurations at lower field (∼ < 1V/μm). They develop into maltese type configuration at higher field (∼ 8V/μm, 10V/μm for PDLC and GHPDLC). It was seen that the optical transmission increases in both cases with increasing temperature. A higher threshold voltage for GHPDLC relative to PDLC films with temperature was noticed. GHPDLC film shows faster switching time (∼ 340 μsec) over PDLC (∼ 510 μsec).

Keywords:

• anthraquinone dye
• droplet morphology
• polymer dispersed nematic liquid crystal
• polymerization induced phase separation

PACS - 61.30:

Acknowledgments

The authors wish to thank M/S Norland, NJ and E. Merck, UK for providing the polymer and liquid crystal materials. We thank to referee for their valuable suggestions. The financial support by CSIR and DRDO New Delhi India, is gratefully acknowledged.