A self-enhanced and recyclable catalytic system constructed by magnetic bi-nano-bionic enzymes for real-time control RAFT polymerization.

Abstract

Environmentally harmful and high-priced initiators such as azodiisobutyronitrile, perchloric acid and butyllithium are usually essential for most of the polymerization technologies such as radical, cationic and anionic polymerizations. Besides, it is also troublesome to achieve complete separation of initiators from obtained polymers. Herein, a recyclable catalytic system for generation of hydroxyl radicals by catalyzing hydrogen peroxide based on bi-nano-bionic enzymes (Fe3O4@Au nanoparticles (NPs)) was successfully constructed. The magnetic and flower-like Fe3O4 NPs provided a recyclable and well-dispersed scaffold for immobilization of Au NPs, leading to enhance catalytic activity of Au bionic enzymes. The designed catalytic system showed excellent catalytic activity for the hydroxyl radical generation in various working conditions (pH 7-11, 15-100 oC). Impressively, the catalytic system was then employed as a novel initiating system (Fe3O4@Au NPs/H2O2) for reversible addition-fragmentation chain transfer (RAFT) polymerization of wide range of functional monomers using different RAFT agents in both aqueous and organic solvents. The established initiating system provided an effective method for RAFT polymerization with real-time control feature in a recyclable way by magnetic separation. It was found that above 93.9% of catalytic activity of Fe3O4@Au still retained after 4 consecutive operations of RAFT polymerization.