Cationic polymerization in liquid sulfur dioxide. I. Cationic polymerization of styrene with SnCl4

Cationic polymerization of styrene in liquied sulfur dioxide was carried out at 0 and 25° using SnCl4 as a catalyst, and polystyrene was obtained very rapidly and in a quantitative yield. Flash polymerization was obtained with concentrations of stannic chloride above 10−2 mole/1. The molecular weight of polystyrene thereby formed ranged from 2 × 104 to 9 × 104 at 0°, much greater than that obtained by cationic polymerization in organic solvents. It was found that {article}{empty}{document}DP{document} (at 0°) depended on [St]/[SnCl4], and it was assumed that the polymerization of styrene by stannic chloride in liquid sulfur dioxide is a cationic polymerization of the “living polymer” type, strengthened by dissociating and solvating characteristics of liquid sulfur dioxide.