Polymerization of olefin oxides and of olefin sulfides

Abstract

AbstractTwo new catalyst systems, sulfur–diethylzinc and 98% hydrogen peroxide–diethylzinc, have been investigated for polymerizing propylene oxide. The sulfur–diethylzinc catalyst system has a broad range of sulfur/zinc atomic ratio for polymerizing propylene oxide heterogeneously to high molecular weight materials in high yields. The highest polymer yield is obtained at the sulfur/zinc atomic ratio of 3–3.5. Like the water–diethylzinc system, the hydrogen peroxide–diethylzinc system has a narrow range of hydrogen peroxide/diethylzinc molar ratio in the vicinity of 0.57 for optimum polymer yield. Crystallinity measurements by x‐ray diffraction of a few polymers prepared with these three catalyst systems showed that they are fairly similar in the extent of their crystallinity. A plot of the per cent of polymer insoluble in acetone against inherent viscosity of the original polymer also showed that the polymers prepared with sulfur–diethylzinc and hydrogen peroxide–diethylzinc catalyst systems have similar amounts of crystallinity. Data are given for the polymerizability of ethylene oxide, 1,2‐butene oxide, styrene oxide, propylene sulfide, 1,2‐butene sulfide, and a vulcanizable copolymer of propylene oxide and allyl glycidyl ether with the sulfur–diethylzinc catalyst system. The polymers from the olefin sulfides had lower inherent viscosities than the polymers from the corresponding olefin oxides. Aging of the sulfur–diethylzinc catalyst (S/Zn atomic ratio = 3.5) improved the yield of poly(propylene oxide). The yield was essentially unchanged when propylene oxide was polymerized in six different solvents. The formation of C2H5SxZnSC2H5 and C2H5SxZnSyC2H5 (x and y are integers between 2 and 8) and possibly C2H5SxZnC2H5 as the catalytically active species is postulated during the reaction of sulfur and diethylzinc.