ZnS:Mn luminescent nanomaterials were first prepared in an inverse microemulsion at room temperature as well as under a hydrothermal condition. Mn-doped ZnS nanoparticles obtained are distributed from 3 to 18 nm in diameter as determined by transmission electron microscopy. The crystalline nature of the materials is clearly demonstrated by the X-ray diffraction results. Compared with Mn-doped ZnS materials synthesized through the conventional aqueous reaction, the nanoparticles prepared in a microemulsion show a significant enhancement in photoluminescence. In particular, the photoluminescence of particles prepared in microemulsion under hydrothermal treatment was found to be enhanced by a factor of 60 as compared to that of the material obtained through the direct aqueous reaction at room temperature. This dramatic increase in photoluminescence yield is attributed to the surface passivation of nanoparticles by the adsorption of surfactants in microemulsion, the formation of sphalerite with cubic zinc blende structure, and Mn migration into the interior lattice of ZnS host.

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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-MA-40 to styrene from 1/2 to 1/8. But the particle size did not seem to be affected by the increase of KPS concentration from 0.5 to 3.0 mM at the feed ratio of 1/8. A polymerization scheme is presented to account for the results.

A modified ternary microemulsion polymerization was successfully used to prepare nanosized polystyrene (PS) microlatexes with high PS/surfactant weight ratios of up to 14:1. Cationic surfactants used were alkyltrimethylammonium bromides, C n TAB, where n is either 12, 14, or 16. A water-soluble initiator was used for the polymerization at room temperature, with moderate stirring. The latexes obtained are bluish-opaque and have been stable now for about 8 months. The process produced rather uniform (D w/D n ≅ 1.10) latex particles of about 40 nm having high molar masses of PS ranging from 1.0 to 2.2 × 106 g/mol. This was obtained by first generating monomer-starved latex particles in a ternary microemulsion containing only 0.5−1.0 wt % styrene and 1.0 wt % cationic surfactant. The subsequent supply of styrene monomer to the polymerized microemulsion was delivered either through dropwise addition or via hollow-fiber feeding of monomer. The latter method was employed for the first time.