Synthesis of monodisperse polystyrene microlatexes by emulsion polymerization using a polymerizable surfactant, ω-methoxypoly(ethylene oxide)40undecyl α-methacrylate macromonomer (PEO-R-MA-40), has been investigated. PEO-R-MA-40 copolymerized readily with styrene. The locus of the copolymerization is believed to occur near the surface of styrene-swollen micelles/particles where the polymerizable end groups (methacrylate) of PEO-R-MA-40 were concentrated due to its hydrophilicity. The latexes became stabilized when only about 6 wt % styrene and 10.5 wt % PEO-R-MA-40 were copolymerized. From the XPS results, it shows that only about 22% of the latex surface occupied by the copolymerized PEO-R-MA-40 was sufficient to stabilize the latex particles. Toward the completion of the copolymerization, about 80% of the latex surface was enriched by the copolymerized PEO-R-MA-40. Nearly monodisperse latex particles with diameters ranging from about 30 to 90 nm were obtained by lowering the feed weight-ratio of PEO-R-M...