Oxygen and Carbon Dioxide Dual Gas-Switchable Thermoresponsive Homopolymers

Herein, we report the first oxygen (O₂) and carbon dioxide (CO₂) dual gas-switchable thermoresponsive polymers based on a newly synthesized monomer N-(2-fluoroethyl amide)-N-(2-(diethylamino)ethyl) acrylamide, that is, AM(F1EA-DEAE), which bears both O₂-switchable fluorinated ethyl amide (F1EA) and CO₂-switchable N,N-diethylamino ethyl (DEAE) moieties on its side chain. PolyAM(F1EA-DEAE) samples prepared from reversible addition-fragmentation chain transfer (RAFT) polymerization exhibited good temperature-responsive properties. Their inherent low critical solution temperature (LCST) could be reversibly tuned to different levels by respectively purging O₂ or CO₂ into its aqueous solution. The O₂-treatment shifted LCST to a higher temperature, while the CO₂-treatment made the polymer fully water-soluble. The polymer could be readily recovered to its initial state by washing off the trigger gas with an inert gas such as nitrogen. This work provides an effective monomer design approach for the preparation of O₂ and CO₂ dual gas-responsive polymers.