Studies of the polymerization of vinyl compounds in the presence of metal salts. 7. Effect of nitric acid on the polymerization of acrylamide initiated by ceric salt

The polymerization of acrylamide initiated by ammonium cerium(IV) nitrate was investigated. The rate was found to vary with concentration of nitric acid. One factor for the variation is the change of concentration of active species of ceric ion by the acid and another factor is the decrease in activity of acrylamide, because the equilibrium constant for the complex of acrylamide with ceric ion decreased with increasing concentration of acid. The rate of initiation was decided by the increasing of activity of ceric ion and by decreasing of that of monomer. The rate of termination was found to increase with increasing activity of ceric ion. From these results, the structure of the complex was proposed; the ceric ion is considered to be coordinated to carbonyl oxygen rather than double bond in acrylamide.