Silyl Triflate-Initiated Ring-Opening Polymerizations of Cyclosiloxanes

Polymer yields between 70 and 85% form in ring-opening polymerizations of trimeric cyclosiloxanes initiated with trimethylsilyl triflate in the presence of a selective scavenger for protic acids, 2,6-di-t-butylpyridine. Examples include the polymerization of 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane (F₃) and hexamethylcyclotrisiloxane (D₃). Siloxane bond redistribution is essentially absent and data are presented establishing a nonterminating polymerization giving an average of roughly one trimethylsilyl group per chain. The present observations contrast with other work that suggests that the presence of free triflic acid is required for initiation with trimethylsilyl triflate.