Synthesis of CO2-responsive polymers by post-polymerization modification

We describe a general method to synthesize a double responsive polymer, exhibiting a temperature and CO2 responsive behavior. The polymer derived from a controlled radical polymerization technique of pentafluorophenyl acrylate (PFPA), followed by a sequential post-polymerization modification of a CO2 responsive- and thermo-responsive amines. Utilizing this approach three double responsive copolymers were synthesized, poly(3-N′,N′-dimethylaminopropyl acrylamide-co-N-isopropyl acrylamide) (poly(DMPA-co-NIPAM)), poly(L-Arginine methyl ester acrylamide-co-N-isopropyl acrylamide) (poly(AME-co-NIPAM)) and poly(L-Arginine methyl ester acrylamide-co-N-cyclopropyl acrylamide) (poly(AME-co-CPAM), respectively. Utilizing turbidity measurement, the stimuli responsiveness of the polymers were investigated and it was found that the lower critical solution temperature (LCST) could be reversibly triggered over a wide temperature range between 6 and 15 °C by purging with CO2 and Ar, respectively. The presented strategy allows the introduction of different functionalities and the control of their fractional amount at the same time and proofs as a versatile platform, leading to adjustable functional polymers.