Abstract
A novel polymer‐dispersed liquid crystal composite film was prepared using liquid crystal and dual resins, namely, UV‐curable urethane diacrylate and thermo‐curable epoxy, with a fixed LC content of 50 wt%. A combination treatment of UV irradiation and heat was performed in sequential steps. At first, the urethane diacrylate resin was cross‐linked through UV irradiation and a pre‐UV‐cured film was formed. Then, the pre‐UV‐cured film was heat treated for curing the thermo‐curable epoxy resin. As the thermal polymerization continued, LC droplets were formed and became embedded within the polymer matrix. PDLC films obtained from the polymer matrix with refractive indices in a range from 1.511 to 1.523 (1.517 ± 0.006) have optimal electro‐optical properties. Films with a refractive index higher than 1.523 have high contrast ratio (CR), threshold voltage (V~th~), and V~90~, whereas those with a low refractive index of 1.508 have low CR, V~th~, and V~90~. In this study, we found that PDLC composite films with optimal compositions prepared by dual resins (UV/thermal) have good electro‐optical properties. © 2007 Wiley Periodicals, Inc. Adv Polym Techn 26:14–20, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20087