Polymer-dispersed liquid crystal (PDLC) belongs to a class of electrically, photonically and thermally activated technologies referred to as ‘Smart Glass’. These technologies mainly include PDLC, suspended particle device (SPD), electrochromic (EC), thermochromic (TC), photochromic (PC), thermotropic (TT) and few other (micro-blinds and nanocrystals) technologies. The PDLC technology had been invented during 1980s by two independent entities in the USA. The first invention based on micro-emulsion method had been patented by J. L. Fergason in 1984 and later in 1987, its exclusive patent rights had been given to Raychem Corporation (USA). Raychem’s spinoff company begun the first commercialisation of this technology since 1987, under ‘nematic curvilinear aligned phase’ (NCAP) trademark. During 1990–1995 period, Raychem had out-licenced its NCAP technology to 3M (USA), Nippon Sheet Glass (JAP) and Saint Gobain (EU).
The second invention was based on phase separation techniques and had been patented by Kent State University (KSU), Ohio (USA) under PDLC trademark in 1987. Also during 1990–1995 period, KSU had outlicenced its PDLC technology to 3M (USA), Polytronix (USA), Asahi Glass (JAP), Ajinomoto (JAP) and Snia BPD/ FIAT Group (EU). The development of these two technologies, now both referred to as PDLC, had been the subject of many academic literature and ongoing industrial developments. The industrial evolution of PDLC technology included an early progress, later decline and recent resurgence periods.