Multicomponent polymerization of elemental sulfur, difluoromethylene phosphobetaine and aryl silyl ethers toward aromatic poly(O,O′-monothiocarbonate)s

Abstract

Polythiocarbonates with similar structures to polycarbonates, have emerged as a group of promising sulfur-containing polymers with a range of practical applications, taking advantages of their excellent optical properties, good thermal stability and film-forming ability, and so on. However, the synthesis of polythiocarbonates generally suffered from mixed isomeric structures of repeating units, and hazardous sulfur-containing reagents. In this work, an efficient multicomponent reaction of elemental sulfur, difluoromethylene phosphobetaine (PDFA), and aryl silyl ethers was designed with the assistance of organic base 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) to produce 12 kinds of O,O′-monothiocarbonate compounds in up to 93% yields, taking advantages of the unique chemical property of difluorocarbene, and the deprotection of silyl group by F⁻ generated from PDFA. Most importantly, the MTBD-assisted multicomponent polymerization of bis(aryl silyl ether)s, elemental sulfur, and PDFA was developed, affording 12 kinds of poly(O,O′-monothiocarbonate)s with well-defined structures, high M_ws of up to 16900 g/mol and high yields (up to 99%). These poly(O,O′-monothiocarbonate)s possessed good film-forming properties and thermal stability, high light refractive indices and transmittance. The facile synthesis of these polymonothiocarbonates might pave the way for the development of promising sulfur-containing polymer materials.