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

Abstract

A novel alicyclic polythiocarbonate with a complex structure sequence has been synthesized by a convenient one-pot polymerization of carbon disulfide(CS_2)and cyclohexene oxide(CHO)with Zn-CoⅢ double-metal cyanide complex(DMCC)as the catalyst.The catalytic activity of the Zn-CoⅢ DMCC could reach to 445 g polymer/g catalyst when the reaction temperature was 100℃ and molar ratio of CHO/CS_2 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 1.1×103～1.3×103 with a molecular weight distribution(MWD)of 1.57～1.71.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 1H and 13 C-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.