Visible Light Photoinitiated Metal-Free Living Cationic Polymerization of 4‑Methoxystyrene

Metal-free, visible light-initiated, living cationic polymerization of 4-methoxystyrene using 2,4,6-tri­(p-tolyl)­pyrylium tetrafluoroborate and methanol is demonstrated. Molecular weight and dispersity are controlled by the concentration of methanol. Initial mechanistic analysis suggests that methanol likely serves to regulate propagation of the cation chain end via reversible chain transfer in a manner analogous to reversible addition–fragmentation chain transfer polymerization.