Synthesis of Sulfur-rich Polymers: Copolymerization of Cyclohexene Sulfide and Carbon Disulfide Using Chromium Complexes

Abstract

An investigation of the copolymerization of cyclohexene sulfide and carbon disulfide using salphen and salen Cr complexes as catalysts and [PPN]+X– salts as cocatalysts, at different temperatures and reaction times, is reported. Both catalytic systems produce both polymer and cyclic products. For the first time, poly(trithiocyclohexylcarbonates) (PCS) have been synthetized in high yields and high molecular weights. Salphen-based catalysts, in comparison with salen-based ones, show higher productivity and selectivity for polymers with high molecular weight up to 18 kg/mol when the reaction is carried out at 25 °C. At a higher temperature with (salphen)CrCl, the maximum value of selectivity for copolymers (72%) was obtained at a short reaction time (3 h). At long reaction times, great amounts of cyclic by-product are observed, thus evidencing the tendency for cyclohexene sulfide and CS2 to provide cyclic products due to the stability of the trithiocyclohexylcarbonate. PCS possesses high refractive index (n > 1.72), and antimicrobial assays reveal that these materials are active against Escherichia coli and moderately active against Staphylococcus aureus. These properties along with the Tg values of 80 °C make these polymers suitable for interesting applications different from those of poly(trithiopropylencarbonate).