Synthesis, characterization, and stimuli-sensitive properties of novel polycarbobetaines

Novel monomers bearing propyl and cyclohexyl groups on the side chain were synthesized from the acetoacetic ester and propylamine and cyclohexylamine. Michael addition reaction with acrylic (methacrylic) acid followed by radical polymerization resulted in preparation of both linear and crosslinked betaine type polyampholytes. The polycarbobetaines were characterized by potentiometric titration, viscometry, GPC, FTIR, NMR, and UV-Vis. The ionization constants of acid and base groups were calculated from the Henderson-Hasselbalch equation. Considerable influence of water content on the yield of linear polymers and swelling degree of hydrogels was established. The dependence of swelling degree on the chain length and concentration of crosslinking agents was found. The stimuli-responsive properties of hydrogels were studied in water-organic solvents mixtures and as a function of pH and ionic strength. The adsorption-desorption recycling stages of hydrogels with respect to copper(II) ions were demonstrated.