Cationic polymerization of vinyl ethers using trifluoromethyl sulfonate/solvent/ligand to access well-controlled poly(vinyl ether)s

Abstract

Cationic polymerization of vinyl ethers to access poly(vinyl ether) polymeric materials has been challenging due to stringent polymerization conditions and inevitable chain transfer. Herein we introduce a protocol using trifluoromethyl sulfonates to catalyze the polymerization of a series of vinyl ethers. These trifluoromethyl sulfonates are fully commercially available and can be stored under ambient conditions. Solvents and ligands have profound influences on the polymerization process, and poly(vinyl ether)s with different molecular weights, molecular weight distributions, and tacticities were obtained. A few combinations of trifluoromethyl sulfonate/solvents/O^O type ligands were explored. They showed high activities and afforded poly(vinyl ether)s with well-controlled tacticity, of which the isotacticity can be up to 81% m. Poly(vinyl ether)s with high tacticities exhibit crystallization behaviors with melting points. We also probed the cationic reversible addition–fragmentation chain transfer (RAFT) polymerization of ethyl vinyl ether employing a RAFT chain transfer agent. Low molecular weight distributions (Đs) around 1.1 can be realized. Since trifluoromethyl sulfonates can be fed at a remarkably low catalyst loading and other chemicals are cheap and easily available, the poly(vinyl ether) polymeric materials are promisingly prepared on a large scale.