Polymerization of Methyl Methacrylate Initiated by Organozinc Compounds

Abstract

The polymerization of methyl methacrylate (MMA) initiated by organozinc compounds (R₂Zn; R=C₂H₅, C₆₂H₅CH₂, or C₅H₂) was carried out in dipolar aprotic solvent such as hexamethylphosphoramide (HMPA) or dimethyl sulfoxide (DMSO). The polymerization initiated by (C₆₂H₅CH₂)₂Zn or (C₅H₂)₂Zn proceeds alone in the presence of large amounts of HMPA, while the polymerization initiated by (C₅H₂)₂Zn does not occur under similar condition. The results obtained from the copolymerization of MMA with styrene initiated by (C₅H₂)₂Zn indicated that the polymerization of MMA initiated by the organozinc compounds proceeds in terms of an anionic mechanism. It was concluded that the coordination of HMPA or DMSO to the zinc atom in R₂Zn increases its ionic character of the zinc-carbon bond and induces the polymerization of MMA. The effects of the structure of R₂Zn and the solvents on the reactivity of R₂Zn were discussed.