Electro–optic studies on polymer-dispersed liquid crystal composite films. I. Composites of PVB–E7

✍ Scribed by A. K. Kalkar; V. V. Kunte; A. A. Deshpande

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 258 KB
• Volume: 74
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19991227)74:14<3485::aid-app23>3.0.co;2-5

✦ Synopsis

The electro-optic performance characteristic of polymer-dispersed liquid crystal (PDLC) composite films out of poly(vinyl butyral) (PVB) and nematic liquid crystal (E7) have been studied for a wide range of PVB-E7 composite compositions (20 -70 wt % of E7). Composites were prepared by solvent casting from chloroform at room temperature. A scanning electron microscopy study showed that a E7 phase is continuously embedded in chink-like structure of PVB matrix. Optical transmittance of the composite films (of 60 and 70 wt % loading of E7) under an alternating current (ac) electric field (0-250, V p-p ) and frequency (50 Hz to 1 KHz) were measured employing HeONe laser ( ϭ 632.8 nm). The results indicate that the (PVB-E7) composite exhibits a memory effect. In the memory state, higher transmittance is preserved without applying voltage. The memory state can be erased and changed to the scattering Off-state by heating the film to the clearing temperature of the liquid crystal.