Synthesis of amorphous copoly(thioether sulfone)s with high refractive indices and high Abbe numbers

New thermoplastic random copoly(thioether sulfone)s with high refractive indices and high Abbe numbers have been developed by the simultaneous introduction of sulfide, sulfone, and alicyclic units in the polymer chains. They were prepared by random copolymerization of 2,5-bis(sulfanylmethyl)-1,4-dithiane (BMMD) and cyclohexane-1,4-dithiol (CHDT) with divinyl sulfone (DVS) based on the Michael polyaddition. Tough, flexible, colorless and transparent copoly(thioether sulfone) (poly(BMMD/CHDT–DVS)) films were obtained, and they showed good thermal stability with the 5% weight-loss at temperatures over 300 °C in nitrogen, and the glass transition temperatures of 42–50 °C. The inherent amorphous nature of films was confirmed by differential scanning calorimetry. Poly(BMMD/CHDT–DVS) exhibited quite high level of refractive indices and Abbe numbers as thermoplastics, in the range of 1.6512–1.6022 and 42.6–50.6, respectively. The experimental refractive indices and their wavelength dispersions were well reproduced by the DFT calculations with the aid of empirical density prediction.