Polyamides Containing Thiadiazole Units:Synthesis and Optical Properties

Highly refractive and transparent polyamides containing thiadiazole units have been developed.These polymers were prepared by a polycondensation reaction of 4,4’-(1,3,4-thiadiazole-2,5-thio) bis(methylene) dibenzoyl chloride(TDTBM-DC) and diamine which contained thioether(―S―) and sulfone units.They showed good thermal stabilities such as a relatively high glass transition temperature of 206-233 °C and a 5% weight-loss temperature(T5%) of 376-395 °C.The optical transmittance of the polymer at 450 nm is higher than 83%.The heterocycle units and plural ―S― linkages provide the polymer with a high refractive index of 1.716-1.725 at 633 nm and a low birefringence of 0.003-0.004.Also they showed improved solubility in polar aprotic solvents and could form moderate strength films with tensile strength of 72.8-83.1 MPa and storage modulus of 1.0-1.8 GPa(at 200 °C).