Effect of Heavy Metal Ions on Polymerization of Methyl Methacrylate Initiated by the Hydroxylamine-H₂O₂ Redox System

Abstract

Effect of iron or copper ions on polymerization of methyl methacrylate (MMA) initiated by the hydroxylamine-H₂O₂ redox system was investigated at 40°C. The rate of polymerization increased significantly in the presence of a trace amount of iron(II) or iron (III), whereas it decreased considerably in the presence of a trace amount of copper(II) (Figs.1, 2and 4). The concentration of H₂O₂ or hydroxylamine (HA) decreased rapidly with time in the presence of iron(II) or iron(III), while in the presence of copper(II) their concentration decreased slightly. In addition, in the presence of copperap the decreasing rate of HA or H₂O₂ was smaller (HA) or larger (H₂O₂) than that in the absence of copper(II)(Figs.5 and 6). These results suggested that (1) the reaction of H₂O₂ with HA followed the formation of free radicals is enhanced by iron(II) or iron(III) and hindered by copper(II), and (2) H₂O₂ decomposes slowly without the formation of free radicals rather than reacting with HA in the presence of copper(II).