The homogeneous radical copolymerization of acrylic with fluoro-acrylic acid was studied at 50°C in water and DMSO as solvents. The compositions found in water were used to calculate the reactivity ratios, i.e. r 1 = 0·37 ± 0·06, r 2 = 1·58 ± 0·10; they were also determined from the kinetic data, i.e. r 1 = 0·50 ± 0·05, r 2 = 0·70 ± 0·05 (copolymerization in DMSO); r 1 = 0·50 ± 0·15, r 2 = 1·50 ± 0·10 (in water). A large difference was found between the reactivities of the co-monomers with the polymeric radicals in water. The acrylic acid radical was found to be more reactive, but the more reactive monomer was fluoro-acrylic acid. The reactivities of radicals and monomers were similar when the copolymerization was carried out in DMSO and this seems to be due to complex formation by the polymeric radicals with the solvent molecules.
