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Effect of Polyelectrolyte Dispersants on the Preparation of Silica‐Coated Zinc Oxide Particles in Aqueous Media
Author(s) -
Wang Hongzhi,
Nakamura Hiroyuki,
Yao Ken,
Uehara Masato,
Nishimura Satoshi,
Maeda Hideaki,
Abe Eiichi
Publication year - 2002
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2002.tb00384.x
Subject(s) - polyelectrolyte , dispersant , chemical engineering , materials science , aqueous solution , surface charge , coating , sodium silicate , isoelectric point , dispersion (optics) , dissolution , zinc , inorganic chemistry , chemistry , polymer , organic chemistry , nanotechnology , composite material , physics , optics , metallurgy , enzyme , engineering
Sodium silicate was utilized to obtain a SiO 2 coating on ZnO particles to prevent a photocatalytic reaction between ZnO and phenol. During the coating process, pH control is important to avoid dissolution of the ZnO as well as to obtain a good dispersion. Two kinds of polyelectrolyte dispersants were used to control the surface charge of the ZnO particles in aqueous media. As a result, poly(ethylenimine) (PEI) shifted the isoelectric point of ZnO from pH 9 to pH 10, whereas poly(ammonium acrylate) (PAA) made the surface charge of ZnO negative between pH 6 and pH 11. The change in the ZnO surface charge produced by adding polyelectrolyte dispersants makes it possible to obtain uniform silica–coated ZnO particle in aqueous media. UV–irradiation experiments showed that PEI, which can make the surface charge opposite to that of SiO 2 , is more effective in obtaining a thick silica coating on ZnO.