Exploration of Poly(thiazole-2-thione) Structures from Multicomponent Polymerizations of Elemental Sulfur, Dichalcones, and Diisocyanides

The exploration of polymer structures with new functional building blocks and their facile syntheses from sustainable feedstocks are long-term challenging tasks for polymer materials. To provide easy access to rarely reported sulfur-containing aliphatic heterocyclic polymers with desired solubility, stability, thermal and optical properties, in this work, an efficient one-pot multicomponent reaction of elemental sulfur, chalcones, and isocyanides was designed to construct thiazole-2-thiones with two types of sulfur atoms, both introduced from elemental sulfur, in high yields (up to 96%). Most importantly, an organic base-assisted multicomponent polymerization of elemental sulfur, dichalcones, and diisocyanides was developed, affording a series of poly(thiazole-2-thione)s with various polymer backbone structures, high molecular weights (M_ns up to 68 500 g/mol), high yields (up to 99%), and high atom economy. Moreover, these unique thiazole-2-thione heterocycles endowed the polymers with excellent solubility, high chemical and thermal stability, and high light refractive indices. This MCP could hence provide a simple, efficient, and robust synthetic approach for poly(thiazole-2-thione)s directly from sulfur, which might accelerate the development of new structures and functionalities of sulfur-containing heterocyclic polymer materials.