Number Of Polystyrene Particles Research Articles

Nanoparticles of Polystyrene Latexes by Semicontinuous Microemulsion Polymerization Using Mixed Surfactants

Nanosized polystyrene (PS) latexes stabilized by the mixture of cationic/cationic, anionic/anionic, or anionic/cationic surfactants of various types with high weight ratios of PS to surfactant (ca. 10:1) have been successfully synthesized by a semicontinuous microemulsion polymerization process. For cationic or anionic systems, spherical latex particles with a weight-averaged diameter (Dw) ranging from about 22 to 53 nm were nearly linearly dependent on the weight ratio of the mixed surfactants with similar charges. Their particle size distributions were rather uniform (Dw/Dn < 1.20). For a system with oppositely charged surfactants at nonequimolar ratios, it could produce stable PS particles up to 94 nm in diameter. High molar masses (Mw) of PS ranging from 1.1 to 1.9 x 10(6) g/mol could easily be obtained for all three systems investigated. For both cationic/cationic and anionic/anionic surfactant systems, the number of PS particles per milliliter of latex (Np) generated in the very early stage of O/W' microemulsion remained rather constant throughout the polymerization. This was controlled by using only 1 wt% of mixed surfactants and the continuous addition of a small amount of styrene. The present polymerization method allows one to synthesize nanoparticles of PS or other polymers of high polymer/surfactant weight ratios at some particle sizes that are unable to achieve them with a single type of surfactant.

Compatibilization of Immiscible Poly(propylene)/Polystyrene Blends Using Clay

AbstractInorganic clay was investigated as a compatibilizer for immiscible poly(propylene)/polystyrene blends. A substantial decrease in the number of polystyrene particles was seen after adding small amounts of an organically treated clay (2–5 wt.‐%) to the blends. A possible mechanism for this kind of compatibilization is discussed, but these unique and completely new findings need further verification.Schematic representation of the intercalated structure in PP/PS/OMMT blends: (a) PP and PS confined in the same gallery of OMMT, and (b) parts of PP and PS molecules located outside the gallery serving as a compatibilizer.magnified imageSchematic representation of the intercalated structure in PP/PS/OMMT blends: (a) PP and PS confined in the same gallery of OMMT, and (b) parts of PP and PS molecules located outside the gallery serving as a compatibilizer.

Polymerization of styrene with ionic comonomer, nonionic comonomer, or both

AbstractNanosized polystyrene latexes with high polymer contents were obtained from an emulsifier‐free process by the polymerization of styrene with ionic comonomer, nonionic comonomer, or both. After seeding particles were generated in an initial emulsion system consisting of styrene, water, an ionic comonomer [sodium styrenesulfonate (NaSS)] or nonionic comonomer [2‐hydroxyethyl methacrylate (HEMA)], and potassium persulfate, most of the styrene monomer or a mixture of styrene and HEMA was added dropwise to the polymerizing emulsion over 6 h. Stable latexes with high polystyrene contents (≤25%) were obtained. The latex particle weight‐average diameters were largely reduced (41 nm) by the continuous addition of monomer(s) compared with those (117 nm) obtained by the one‐pot polymerization method. Latex particles varied from about 30 to 250 nm in diameters, whereas their molar masses were within 104 to 105 g/mol. The effect of the comonomer concentration on the number of polystyrene particles per milliliter of latex and the weight‐average molar masses of the copolymers during the polymerization are discussed. The surface compositions of the latex particles were analyzed by X‐ray photoelectron spectroscopy, which indicated that the surface of the latex particles was significantly enriched in NaSS, HEMA, or both. © 2001 John Wiley &amp; Sons, Inc. J Polym Sci A: Polym Chem 39: 1634–1645, 2001

Microanalysis of the surface concentration of sulfate groups at polystyrene particle by isothermal titration calorimetry

Microanalysis of sulfate groups at polystyrene particle surfaces, which were derived as persulfate initiator fragments, was carried out with isothermal titration calorimetry, and compared with a conventional conductometric titration. The quantitative analysis was possible even with an extremely small number of polystyrene particles have 10 μmol sulfate groups.