Photocontrolled iodine-mediated reversible-deactivation radical polymerization with a semifluorinated alternating copolymer as the macroinitiator

Abstract

A new photocontrolled iodine-mediated reversible-deactivation radical polymerization (RDRP) strategy to facilely prepare main-chain-type semifluorinated alternating block copolymers was successfully established under irradiation with blue LED light at room temperature, by using a semifluorinated alternating copolymer ((AB)_n, where A represents α,ω-diiodoperfluoroalkane and B represents α,ω-unconjugated diene) as a macroinitiator and chain-transfer agent, and methacrylates, acrylates and styrene as the monomers. The end group of (AB)_n terminated with perfluoroalkyl iodide –(CF₂)_n–I can be activated by Ru(bpy)₃Cl₂/AsAc-Na reducing quenching catalytic cycle which generates initial carbon centered radicals (–(CF₂)_n˙) to initiate the polymerization under blue LED light irradiation. The polymerization can reach a reversible equilibrium through effective oxygen–iodine halogen bonding in acetone and undergo a photocontrolled iodine-mediated RDRP process. In addition, the “living” features of this photocontrolled iodine-mediated RDRP system were confirmed by polymerization kinetics and controlled “on–off” light switching cycle regulation. What's more, different types of fluoropolymers can be introduced on the copolymer chains due to the powerful designability of (AB)_n. Therefore, this strategy can provide a facile and highly efficient approach to the precision synthesis of main-chain-type semifluorinated alternating di/triblock polymers under visible light irradiation.