Polymerization of methyl methacrylate in ternary oil-in-water microemulsions

Abstract

Polymerization of methyl methacrylate has been studied in ternary o/w microemulsions that were stabilized by stearyltrimethylammonium chloride. The latices produced still remain transparent and stable about one year after preparation. It is calculated that each small latex particle of hydrodynamic radius ( R h) ranging from 20 to 24 nm contained two or three polymer chains of high molecular weight of 5 to 8 million. The rate of polymerization shows only two intervals for most of the systems. This corresponds to the rates of nucleation and growth of particles. But a constant rate of polymerization is also noted for the first time for microemulsions containing a lower concentration of initiator and/or at a lower temperature ( T<55°C). A possible mechanism related to rates of free-radical generation and polymerization is proposed to explain this constant rate of polymerization in a microemulsion.