PRODUCTION OF MONODISPERSE COLLOIDAL SILICA SPHERES - EFFECT OF TEMPERATURE

In general, particles produced in ethanol and n-propanol exhibited the strongest temperature dependence, especially at low temperatures At elevated temperatures, the particle size varied directly with the chain length of the alcohol but, under cooler conditions, this tendency appeared to reverse itself except in the case of methanol. This complex behavior is not easily explained but it is probably related to the different effects temperature has on such solution properties as solubility and viscosity. The most important result demonstrated by this study is that, by using a single alkyl silicate (commercially available TEOS) along with a short-chain alcoholic solvent (ethanol or n-propanol), and by simply varying the reaction temperature, it is possible to produce uniform silica spheres over a wide range of sizes (0. 2-2. 0 mu m). The particles made in this fashion are relatively monodisperse, with the size distribution becoming wider as the temperature is increased.