The regulation of polymer structures and electro-optical properties of epoxy-mercaptan-based phase separated liquid crystals / polymer composites

Morphologies of polymer networks are playing a key role in affecting the electro-optical (E-O) properties of a polymer dispersed liquid crystals (PDLCs) material. In this paper, the relationships between the polymer morphologies and the E-O properties of PDLCs are investigated in an unexplored thermally curing system based on epoxy/low-molar-mass-mercaptan. The polymer morphologies in this curing system can be regulated from polymer beads to porous polymer matrix by varying the liquid crystals (LCs) contents, chemical structures of epoxy monomers, and functionality of thiol hardeners. Interestingly, great improvements of E-O properties occur as the polymer structures change from polymer beads to porous frameworks, even though with an abnormal low LCs contents. Eventually, the mechanism for the formation of different polymer structures are illustrated and the relationships between the E-O properties and polymer structures are established. This work provides new insights in morphology control and optimizing the E-O properties in thermally cured PDLCs films.