Investigating the Degradability and Optoelectronic Properties of π-Conjugated Polymers with 1,2,4-Chalcogenadiazole Linkers

Abstract

As the world is now facing the inevitability of forever plastics, all new high-performance polymers require careful design. Building on our previous work on the degradable 1,2,4-oxadiazole linker for conjugated polymers, we investigate the effects of chalcogen substitution in the linker on the optoelectronic and degradation properties of the π-conjugated polymers. Small molecule models were used to demonstrate the photodegradation of the linkers in the presence of methanol. The syntheses of polymers containing 1,2,4-thiadiazole and 1,2,4-selenadiazole linkers by direct heteroarylation polymerization are reported. As heavier chalcogen atoms are substituted into the 1,2,4-chalcogenadiazole linker, the optical HOMO–LUMO gap becomes smaller. This effect is due to the stabilization of the HOMO and destabilization of the LUMO as heavier chalcogen atoms are substituted. The polymers incorporating the 1,2,4-oxadiazole and 1,2,4-thiadiazole linkers show evidence of photodegradation by ¹H NMR and gel permeation chromatography.