1992 Volume 100 Issue 1165 Pages 1140-1144
Effects of hydrolysis-rate-control-additives (carbonyl compounds such as ethylacetoacetate and acetylacetone) on the hydrolysis behavior of aluminium secondary butoxide and condition for the formation of monodispersed alumina particles were investigated. The reactive enol form of the carbonyl compounds substituted butoxyl group of aluminium secondary butoxide and chelated the aluminium atom. The chelating ligand would not be easily removed upon hydrolysis reaction because the aluminium-ligand bond was sufficiently strong. As a consequence, the rate of hydrolysis and polycondensation of modified precursor decreased. By hydrolyzing this modified stable precursor, the monodispersed alumina particles were prepared in the wide range of water concentration; about 8 times that of non-modified precursor when 0.006mol/l ethylacetoacetate was added and about 4 times when 0.006mol/l acetylacetone was added. The average particle size of obtained monodispersed particles and the geometrical standard deviation were 0.2μm and 1.18, respectively. The morphology of particles changed with increasing water concentration as follows; agglomerates of coarse texture→monodispersed particles→agglomerates of fine texture.
