Cationic RAFT Polymerization of Isobutyl Vinyl Ether with Organotellurium Catalysts

The cationic reversible addition–fragmentation chain-transfer polymerization of isobutyl vinyl ether was carried out using S -1-isobutoxyethyl N, N -diethyl dithiocarbamate as the initiator and chain-transfer agent. The chalcogen bonding catalysts POxTe-TfO, DTolTe-SbF 6, POxTe-SbF 6, and TeVio-TfO gave polymers, and polymers with a narrow molecular weight distribution ( M w / M n < 1.2) were obtained with catalysts containing the SbF 6 anion. Polymerization exhibited an induction period using the catalyst at low concentration. The catalytic activity depended on the electron deficiency of the cationic tellurium framework and the nucleophilicity of the counteranion. Polymerization using DTolTe-SbF 6 gave polymers with number-averaged molecular weights up to 20,000 while maintaining a narrow molecular weight distribution. In this polymerization system, alcohol elimination from the main chain was significantly suppressed. Interestingly, irradiating TeVio-TfO with a blue light-emitting diode improved the catalytic activity and accelerated polymerization, likely due to intramolecular charge transfer from the tellurium atom to the viologen skeleton in the excited state.