The influence of the polymer matrix on the liquid crystal droplet configuration within a polymer-dispersed liquid crystal (PDLC) film is studied with the use of infrared spectroscopy. With a change of the polymer from poly(n-butyl methacrylate) to poly(isobutyl methacrylate) with the use of E7 liquid crystal, the droplet configuration changes from bipolar to radial. For both of these PDLC systems with 80:20, 70:30, and 60:40 E7/polymer compositions, the LC droplets grow in diameter with time. The spectroscopic data monitoring the droplet growth are described exponentially. A transition temperature is observed as both types of PDLCs cool, forming droplets by the thermally induced phase-separation technique. The TN-I transition for the E7/PBMA PDLC appears at 46°C and for the E7/PIBMA PDLC appears at 51°C.
Coleen A. McFarland, Jack L. Koenig, and John L. West, "Influence of the Polymer Matrix on the Bipolar and Radial Droplet Configurations within PDLC Films Examined by Infrared Spectroscopy," Appl. Spectrosc. 47, 598-605 (1993)