Structural Definitions for Soluble Portions of Polyacrylamides Synthesized with Ce(IV)–Chelating Agent Redox Systems

Abstract

Polymerizations of acrylamide initiated by ceric ammonium nitrate and ceric sulphate in combination with nitrilotriacetic acid, ethylene diamine tetraacetic acid, diethylene triamine pentaacetic acid and 1,2-cyclohexane dinitrilotetraacetic acid were studied in aqueous nitric acid and sulphuric acid solutions at 55°C in the presence of air. The experimental results can be explained by assuming that the complexes of Ce(III) with sulphate and nitrate ions, C(SO 4 ) n x(+ or -) and Ce(NO 3 ) n x(+ or -) , have different reactivities in the reactions. FTIR and UV spectra of the polymers, together with conductometric and gravimetric measurements, clearly showed that in the case of sulphato-cerate complexes, there were complexes not only on the end-groups but also on amide groups within the chain. Furthermore, it was observed that the stabilities of the primary radical sources generated by the redox pairs used in this work depend on the anion type and concentration of the acid and oxidation agent.