Oxygen-switchable thermo-responsive random copolymers

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.