COPOLYMERIZATION OF CARBON DISULFIDE AND CYCLOHEXENE OXIDE WITH A DOUBLE-METAL CYANIDE COMPLEX CATALYST

A novel alicyclic polythiocarbonate with a complex structure sequence has been synthesized by a convenient one-pot polymerization of carbon disulfide (CS2) and cyclohexene oxide (CHO) with Zn-Co-III double-metal cyanide complex (DMCC) as the catalyst. The catalytic activity of the Zn-Co-III DMCC could reach to 445 g polymer/g catalyst when the reaction temperature was 100 degrees C and molar ratio of CHO/CS2 was 2. Further increasing or decreasing the temperature resulted in a decrease in the catalytic activity. The weight-average molecular weight (M-w) of the obtained copolymer was in the range of 1.1 x 10(3) similar to 1.3 x 10(3) with a molecular weight distribution (MWD) of 1.57 similar to 1.71. The copolymer has terminated -OH and -SH groups from the results of FTIR spectrum and Raman spectrum. Furthermore, one carbonate unit -O (O) CO-, and four thiocarbonate units -S (O)- CO-, -S(O)CS-, -S(S)CO-, and -S(S)CS- in the copolymer were found from H-1 and C-13-NMR spectra, and the monothiocarbonate unit (-S(O)CO-) was the main unit in the copolymer,which was consistent with the results from FTIR spectrum. Cyclohexene sulfide, which was a direct evidence for O-S atom-exchange reaction, was detected by GC-MS technique from the products. Only hexahydro-benzo[1, 3]oxathiol-2-one, hexahydro-benzo [1, 3] dithiol-2-one, and hexahydro-benzo [1, 3] dithiole-2-thione (theoretically six five-membered cyclic products) were detected due to the monomer structural factors and thermodynamical factors. The copolymer chain structure and variety of cyclic products indicates that an O-S atom-exchange reaction existed in the copolymerization. Further efforts and experiments are on going in order to further explore the mechanism of the atom-exchange copolymerization and with a view to synthesizing a sulfur-containing polymer with high molecular weights, controllable stereochemical structures, as well as high catalytic activity.