Synthesis and characterization of poly(propylene sulfite) from sulfur dioxide and propylene oxide using zinc derivatives as catalysts

Abstract

The zinc glutarate catalyzed copolymerization of sulfur dioxide (SO2) and propylene oxide (PO) was investigated in detail by varying temperature, time, monomer feed ratio, and PO feed per catalyst as well as by using solvents, such as PO and chloroform. An optimized copolymerization [PO]/[catalyst] = 300, and no solvent at 60 degrees C, 40 h. [PO]/[SO2] = 1, resulted in poly(propylene sulfite) (PSS) with high molecular weight (M) over bar(n) = 42000 ((M) over bar(w)/(M) over bar(n) = 2.1) never achieved before. PPS was obtained in a yield of 66.9 g per g of catalyst (namely, 12.93 kg per mol of catalyst) and determined to consist of 90.4 mol-% sulfite-linkage and 9.6 mol-% ether-linkage. A polymer amount of ether-linkages was additionally formed as a minor component. However, no formation of cyclic propylene sulfite as byproduct was detected. In addition, zinc hexacyanoferrate(III) was prepared and used in the copolymerization as a catalyst, but showed almost no catalytic activity.