Polymer Dispersed Liquid Crystals

A polymer dispersed liquid crystal (PDLC) is a two-phase system containing liquid crystal (LC) domains, usually in the form of droplets, which are embedded into a polymer matrix. During the past three and a half decades, this subject has been of continuous interest and intense study. It is useful in various applications, such as smart windows, light shutters, modulators, sensors, optical switches, holographic films, flat-panel displays, etc. In developing PDLC films for intelligent opto-electronics applications, the main objective is to prepare a PDLC with a high contrast ratio, a low threshold voltage and a low switching time. However, in spite of a great deal of work on PDLC and related materials, it is still of much open interest. The main focus of the present chapter is to provide a comprehensive view on various aspects of PDLCs, such as the preparation of conventional PDLCs, their characterization and properties, morphological, electro-optical and temporal behavior and applications. Usually, the PDLC technology utilizes nematic liquid crystals providing switching between a translucent and a transparent state because of refractive index mismatching. The PDLCs developed using the cholesteric and ferroelectric liquid crystals, known as PDCLCs and PDFLCs, respectively, are also discussed.