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

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 alpha,omega-diiodoperfluoroalkane and B represents alpha,omega-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)(3)Cl-2/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.