Effects of Water Adsorption on Dispersibility of Fumed Silica in Mixed Organic Solvents of Ethanol and Hexane

Abstract

Fumed silica has been widely used as various applications to improve functionalities. In order to achieve the desired effect of fumed silica, it is important to control fumed silica dispersion and aggregation behaviors. Although silanol groups on fumed silica surface are water attractive and that strongly affects dispersibility especially in different humid atmosphere, there have been few reports to investigate the relationship between adsorbed water of fumed silica surface and dispersibility. In this experiment, we studied dispersibility of fumed silica, whose surface was controlled of water adsorption, in the mixture of hexane and ethanol with different polarities. In relative permittivity of 15.48, there is a different tendencies between relative humidity of 50.8% and 56.8%. It seems that dispersion and aggregation behaviors are associated with amount of the adsorbed water and polarity in the systems. A small amount of adsorbed water could improve dispersibility in certain polarity.