Selective modification of kaolinite with vinyltrimethoxysilane for stabilization of Pickering emulsions

Amphiphilically modified kaolinite was produced by the modification of the octahedral surface of kaolinite with vinyltrimethoxysilane for use in the stabilization of Pickering emulsions. The covalent grafting of the hydrolysate of vinyltrimethoxysilane on the kaolinite octahedral surface resulted in kaolinite exhibiting dual-surface affinity. Further, the surface wettability of the modified kaolinite could be tuned by regulating the reaction temperature. Investigations of emulsions stabilized using the modified kaolinite samples indicated that the emulsion stability was significantly higher. In addition, the phenomenon of phase inversion could be controlled based on the wettability of the modified kaolinite. The highest stability of emulsion was observed when the emulsion droplet size was the lowest and the emulsion viscosity was the highest at the phase-inversion point. These findings should lead to the development of methods for preparing amphiphilic surface-active emulsifiers as well as the production of the desired types of emulsions at a given water/oil ratio.