A novel approach to cyclic polysulfides via the controlled ring-expansion polymerization of cyclic thiourethane with thirianes

The study was conducted to demonstrate the synthesis of new cyclic polymers with controlled molecular weight by the continuous insertion reaction of thiirane into cyclic thiourethane. The continuous insertion reaction of thiirane into linear thiourethane was examined in the presence of tetrabutylammonium bromide (TBAB) as a catalyst in NMP for 24 h with the various feed molar ratio of phenoxypropyrene-sulfide (PPS) and phenyl benzenethiocarbamate (PBT). The extent of the continuous insertion reaction (DI) of PPS into the thiourethane moiety was calculated that based on the signals of the -NH- protons at 10.42 ppm and methylene protons of -CH2O- moieties produces by the insertion reaction of PPS at 4.06-4.13ppm. It was found that DI value coincided with the feed ratio of PPS that was 50.0. It was concluded that the insertion reaction of the PPS into the thiourethane moiety of Thiourthane thioazolidine-2,4-dione (TZD) proceed selectively and without any inter-or intra and exchange reaction of the thiourethane moieties.