The development of highly efficient monophosphonium photocatalysts for the visible light-regulated metal-free cationic polymerization of vinyl ethers

A class of monophosphonium photocatalysts is developed via the assembly of phosphines and alkynes, and demonstrated as efficient organic photoredox catalysts for the visible light-mediated cationic reversible addition-fragmentation chain transfer (RAFT) polymerization of vinyl ethers. This organocatalytic process can be carried out at a low catalyst loading (5-20 ppm), affording metal-free and well-defined poly(vinyl ether)s with predictable molecular weight and narrow dispersity in short reaction times. Remarkably, these photocatalysts could regulate the chain-growth by light with a strict temporal control, and also allow a preliminary correlation between the structure/property of the catalysts and their catalytic performance.