Liquid Crystal Dispersed in a Polymer Matrix

Both polymers and liquid crystals belong to a class of matter, sometimes called condensed matter, complexing fluids, soft matter [32-34], extensively studied in recent years in terms of their behavior and physical-chemical properties. Unlike gases and liquids, soft materials exibit a certain form (polymer) or internal organization (liquid crystal) but, in contrast to hard materials, they strongly respond to external mechanical (polymer) or electric (Uquid crystal) disturbances. 

Combining outstanding mechanical properties of the polymer film (high mechanical strength and flexibility) with interesting optical properties of liquid crystal (high optical anisotropy), the PDLC systems allow their use in various applications as flexible display systems, privacy or smart glass, projection devices, sensors, etc.). 

3 Techniques for Obtaining Liquid Crystals Dispersed into a Polymeric Matrix 

The literature of the field proposes several methods for obtaining PDLC films, grouped as emulsion and phase separation techniques. In the first case, the liquid crystalline droplets are formed in the liquid phase while, in the second case, droplets are formed later, during film solidification. The PDLC film behavior depends on the preparation technique, droplet size, droplet shape, phase contamination, film thickness, film aging. 

Ihe emulsion technique introduced by Fergason [48, 49] is recognized as the first method for obtaining PDLC systems, even if the term as such was introduced later. 

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