Oxygen-switchable thermo-responsive random copolymers

Abstract

In this paper, we report the synthesis of oxygen (O₂)-switchable thermo-responsive random copolymers based on fluorinated acrylamide monomer homologues: N-(2-fluoroethyl)acrylamide (F1EA), N-(2,2-difluoroethyl)acrylamide (F2EA), and N-(2,2,2-trifluoroethyl)acrylamide (F3EA). Copolymerizing these monomers with N,N-dimethylaminoethyl methacrylate (DMA) via reversible addition–fragmentation chain transfer (RAFT) polymerization yields thermo-responsive random copolymers, which have dual switchability towards O₂ and carbon dioxide (CO₂). The inherent low critical solution temperature (LCST) of these copolymers can be precisely designed in a wide range of temperatures by varying their chemical compositions. Importantly, this LCST can be reversibly switched to different levels by respectively purging O₂ or CO₂ into the aqueous solution, and can be recovered to its initial state by washing off the trigger gas. This work provides a versatile and effective approach for the preparation of O₂-responsive polymers, with a big operation window of temperature.