General Strategy for Making CO2-Switchable Polymers

By discovering that poly( N, N -dimethylaminoethyl methacrylate) (PDMAEMA) in water can react with carbon dioxide (CO 2 ) and have its lower critical solution temperature (LCST) reversibly tuned by passing CO 2 and argon (Ar) through the solution, we describe a general strategy for imparting a CO 2 -switchable LCST or water solubility to polymers of broad interest like poly( N -isopropylacrylamide) (PNIPAM) and poly[2-(2-methoxyethoxy)ethyl methacrylate] (PMEO 2 MA). We show that by easy copolymerization incorporating DMAEMA as a CO 2 -responsive trigger into PNIPAM or PMEO 2 MA, their LCST can effectively be switched by the gases. Two examples of applications were further demonstrated: upon CO 2 or Ar bubbling at a constant solution temperature, hydrogels could undergo a reversible volume transition and block copolymer micelles could be dissociated and reassembled. This study opens the door to a wide range of easily accessible CO 2 -switchable polymers, enabling the use of CO 2 as an effective trigger for smart materials and devices.