Phase behavior and polymerization of styrene and (meth)acrylate in oil-in-water micellar solutions

The phase behavior of the micellar solutions of styrene stabilized by sodiu m dodecyl sulfate (SDS) in the presence of cosolvent such as I-pentanol (PO L), butyl acrylate (BA) and dodecyl methacrylate (DMA) was investigated. At a relatively low level of POL the spontaneous emulsification of styrene (S t) appears. The addition of excessive POL, however, promotes the fort-natio n of gel-like and milky emulsion products. The phase behavior upon the addi tion of alcohols may be the result of two competing factors: the stabilizin g effect of micelles due to the micellization of alcohols with interfacial droplet layer versus the destabilizing effect resulting from transformation of isotropic droplets to anisotropic ones and disruptive change of the str ucture of water. The synergistic effect of BA increases with increasing SDS concentration. The poisoning effect of DMA on the colloidal parameters res ults from the depressed water solubility of reactants, increased hydrophobi city of amphiphile system, accumulation of monomer and additive in the drop let core and swelling effect. The size of polymer particles is independent of the initial droplet size. The final monomer conversion decreases with in creasing concentration of POL or DMA and aging time of the monomeric emulsi on. The broad droplet size distribution, however, excludes the scenario tha t nucleation takes place primarily in the microdroplets or the aqueous phas e (homogeneous nucleation). The mixed mode of particle nucleation (monomer droplet nucleation and micellar nucleation or homogeneous nucleation) and d epressed transfer of monomer from the highly monomer-swollen particles to t he reaction loci are postulated to govern the kinetic and colloidal paramet ers of the emulsion polymerization of St with BA or DMA.