Role of surfactant in composite latex particle morphology

摘要

AbstractComposite particles were prepared by seeded emulsion polymerization at 70°C using K2S2O8as initiator and two different nonionic surfactants. Monodisperse polystyrene latex particles were used as seed and methyl methacrylate was used as second‐stage monomer. When the surfactant, polyethylene oxide–propylene oxide (Pluronic F‐108), was used, the final particle morphology showed that the PMMA (core) was partially covered by polystyrene. However, when nonyphenol polyethylene oxide (Igepal Co‐990) was used as surfactant, one observed a reversed type of encapsulation (i.e., PS core is partially engulfed by PMMA). The interfacial tensions of the polymer phase against water containing the appropriate surfactant were measured by the drop‐volume method and used in a mathematical model based on thermodynamic analysis to predict the equilibrium particle morphology. The observed particle morphologies were found to differ from the predicted morphologies at low conversion of the second‐stage monomer but agreed with it at highe