Synthesis and mesomorphic properties of side chain liquid crystalline polymers having thiadiazole ring

Abstract

New liquid crystalline monomers having 1,3,4-thiadiazole ring as mesogen were synthesized by using Lawesson's reagents to prepare the thiadiazole ring and acryloyl chloride and methacryloyl chloride to introduce the vinyl group. These monomers were polymerized in the presence of 2,2'-azoisobutyronitrile as initiator in THE All monomers and polymers show cholesteric behavior and a broad chiral smectic C* phase. As the spacer length increases, the phase transition temperature is lowered and the polymers show higher phase transition temperatures and improved mesophase stabilities compared to the corresponding monomers.