Visible Light-induced Living Cationic Polymerization Using Boranil Complex as a Robust Photocatalyst.

The development of efficient and robust photocatalysts is critical to achieving photomediated cationic polymerization with good control. Herein, we introduce a novel family of photocatalysts based on the boranil skeleton, which enables a visible-light-mediated cationic polymerization of vinyl ethers under operationally simple conditions, affording polymers with well-controlled molecular weights and low dispersities. Mechanistic experiments and computational studies were conducted to rationalize the catalysis and initiating mechanism, and interestingly, extra activation resulting from the photoinduced opening of boric Lewis acid site was found also operative, enabling the good tolerance of this system to air and moisture. Further application of this photopolymerization method to photocuring and photopatterning is also demonstrated with success.