Copolymer composition-dependent light transmission of polymer/liquid crystals composite films

✍ Scribed by Byung Kyu Kim; Seon Hee Kim

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 334 KB
• Volume: 36
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(19980115)36:1<55::aid-polb7>3.0.co;2-t

✦ Synopsis

Electrooptic responses (voltage and angular-dependent transmittance) of polymer/liquid crystal composite films with H, V, and unpolarized lights have been studied based on a nematic liquid crystal (Ro-5921) and four types of homopolymers and copolymers from ethyl methacrylate and styrene with different compositions. In this way, the index ratio of the polymer ( n p ) to the ordinary refractive index of liquid crystal ( n o )(n p /n o ) has been varied systematically, and the effect of the index ratio on viewing angle, applied voltage, response times, and transient response have been investigated. With increasing styrene content in the copolymer, droplet size increased, threshold (V th ) and saturation (V sat ) voltage, and rise time decreased. With n p © n o , maximum transmittance occurred at normal incidence, regardless of the type of polarization. On the contrary with n p ú n o , V-polarization gave a peak in the transmittancevoltage curve, and transmittance overshot upon removal of the field, and these were interpreted in terms of effective refractive index and two-step relaxations.