Polystyrene-Silica Colloidal Nanocomposite Particles Prepared by Alcoholic Dispersion Polymerization

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• 作者：Andreas Schmid ; Syuji Fujii ; Steven P. Armes ; Carlos A. P. Leite ; Fernando Galembeck ; Hideto Minami ; Naohiko Saito ; Masayoshi Okubo
• 刊名：Chemistry of Materials
• 出版年：2007
• 出版时间：May 15, 2007
• 年：2007
• 卷：19
• 期：10
• 页码：2435 - 2445
• 全文大小：997K
• 年卷期：v.19,no.10(May 15, 2007)
• ISSN：1520-5002

文摘

Micrometer-sized silica-stabilized polystyrene latex particles and submicrometer-sized polystyrene-silica nanocomposite particles have been prepared by dispersion polymerization of styrene in alcoholicmedia in the presence of a commercial 13 or 22 nm alcoholic silica sol as the sole stabilizing agent.Micrometer-sized near-monodisperse silica-stabilized polystyrene latexes are obtained when the polymerization is initiated with a nonionic AIBN initiator. These particles are stabilized by silica particles thatare present on the latex surface at submonolayer concentration. The total silica content is no greater than1.1 wt %, which corresponds to a silica sol incorporation efficiency of less than 1.3%. Reduction of theinitial silica sol concentration led to a systematic increase in the mean latex diameter. In contrast, submicrometer-sized polystyrene-silica nanocomposite particles are obtained when the polymerization isinitiated with a cationic azo initiator. The silica contents of these nanocomposite particles are significantlyhigher, ranging up to 29 wt %. Zeta potential measurements, XPS, and electron spectroscopy imagingby transmission electron microscopy (ESI/TEM) studies reveal a well-defined core-shell morphology for these particles, whereby the core is polystyrene and the shell comprises the silica sol. Aftercalcination, these nanocomposite particles can form hollow silica capsules. Variation of the initial silicasol and initiator concentration has relatively little effect on the final particle size and silica content ofthese polystyrene-silica nanocomposite particles, but indicates silica sol incorporation efficiencies up to72%.