Design of smart polyacrylate showing thermo-, pH-, and CO2-responsive feature
A novel acrylate monomer 2-((3-(isopropylamino)-3-oxopropyl)(methyl)amino)ethyl acrylate (IMA) was synthesized by facile sequential two-step reactions and polymerized utilizing reversible addition-fragmentation chain transfer (RAFT) polymerization to yield the thermo-, pH- and CO2-responsive homopolymer PIMA with well-defined structure. PIMA showed a lower critical solution temperature (LCST) close to body temperature, and the influence of the degree of polymerization (DP), polymer concentration, salt concentration and substituents on LCST was investigated. Due to the tertiary amino groups in the side chains, the thermoresponsive phase transition of PIMA was tunable by solution pH and bubbling CO2/N2. The LCST increased with decrease of pH, and the solubility of PIMA (at temperature above the LCST) could be reversibly switched back by bubbling CO2/N2.