MICROEMULSION RADICAL POLYMERIZATION OF ALKYL ACRYLATES

The oil/water microemulsion polymerizations of alkyl (methyl (MA), eth yl (EA), butyl (BA), hexyl (HA) and 2-ethylhexyl (EHA)) acrylates init iated by a water-soluble (ammonium peroxodisulphate (APS)) initiator w ere investigated. The rate of polymerization versus conversion curve s hows two inconstant intervals. The maximum rate of polymerization of M A, EA, BA and EHA is found to be proportional to the 0.53, 0.17, 0.46 and 0.59 powers of the APS concentration and to the first power of the monomer (MA, BA and EHA) concentration. Homogeneous (solution) radica l polymerization is operative in the MA, BA and EHA systems. The stron g rate dependence on the EA monomer concentration is assumed to be cau sed by both the polymerization within the micelle core and the gel eff ect. The particle size was observed to increase with conversion in the EA and BA runs and to decrease in the EHA and HA runs. The number of particles increased with conversion during the whole polymerization. T he polymer particles grow by recruiting monomer and emulsifier from th e free monomer-swollen micelles and dead particles.