Alternating Copolymerization of Epoxides and Isothiocyanates to Diverse Functional Polythioimidocarbonates and Related Block Polymers

Synthesis of diverse polythioimidocarbonates via ring-opening copolymerization of epoxides and isothiocyanates catalyzed by or-ganoboron catalyst was reported herein.Both aromatic and aliphatic isothiocyanates underwent successful copolymerization with terminal and internal epoxides,allowing for the precise tuning of the performance of the resultant copolymers over a broad range.The wide scope of available isothiocyanates and epoxides enables the direct construction of sulfur-containing functional polymers featuring both high glass transition temperature and refractive index.Additionally,it was observed that aromatic isothiocyanates polymerize much faster than aliphatic ones,and the reactivity difference facilitated the one-step synthesis of block polymers from mixed aromatic isothiocyanates,aliphatic isothiocyanates and epoxides due to the preferential incorporation of aromatic isothio-cyanates over the aliphatic analogues during their alternating copolymerization with epoxides.The produced polythioimidocar-bonates can be used as positive resists for electron beam lithography(sensitivity of 130 μC/cm2 and contrast of 1.53 for poly(CHO-a/t-EITC)).Coupling with their high refractive index(1.58-1.68),polythioimidocarbonates might find functional applica-tions in optics.These results render ring-opening copolymerization of epoxides and isothiocyanates a facile route to enrich function-al polymer library.