Solvent effects on the copolymerization kinetics of ionic (AMPS) and non-ionic (HEAm) acrylamide derivatives

The free-radical copolymerization of two N-substituted acrylamide monomers, the ionic AMPS (2-acrylamido-2-methyl-1-propanesulfonic acid) and the non-ionic HEAm (2-hydroxyethylacrylamide) is presented. Despite bearing similar polymerizable functionalities, HEAm is more reactive toward free-radical addition than AMPS in water. In a mixed aqueous solvent containing salt, (0.5 M LiNO₃, 50 wt%) and ethanol (50 wt%), the reactivity ratio was found to be r_AMPS = 0.53 and r_HEAm = 1.06 indicating that copolymers with a nearly random distribution of sulfonic and hydroxy functionalities can be prepared.