Coacervates of polyvinyl alcohol) have been prepared using colloidal silica as the core material (Iler, 1973, 1974). The coacervate was prepared from a dilute aqueous solution of the polymer and colloidal silica at pH 10. The pH was lowered to 2.6 with HC1 and deaerated with a mixture of dodecyl alcohol and propyl alcohol, boiled in a vacuum and cooled to 25°C to form the coacervate. The maximum yield of coacervate was obtained when the ratio of colloidal silica to polymer in the coacervate was proportional to the particle diameter. For every nm2 of colloidal silica surface, there were 2.5 hydroxy-ethyl chain segments. The coacervate consisted of silica particles whose surface was covered with a monomolecular layer of the polymer. The hydroxyl groups of the polymer were bonded to the SiOH group on the silica surface so that the hydrocarbon chain formed a hydrophobic coat.
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