Control of micro-spheroid silica structure and organic functionalization via a sol-gel method in W/O emulsion

Abstract

A controlled fabrication of silica materials with micro-spheroid type of structure containing a layer of organic functional groups outside the surfaces by using a sol-gel method in W/O emulsion was designed. The presence of Pluronic P123 and surfactants during the acid-catalyzed condensation greatly influenced the final particle morphology. When Pluronic P123 copolymer was used in the W/O emulsion under the low pH condition, 2 or 3 of water droplets were linearly arranged and inter-condensation of hydrolysed TEOS molecules occurred. Depending on the surfactants such as non-ionic (Span 80 or AOT), anionic (SDS), cationic (CTAB), used in the aqueous phase, the particle morphology was changed because of the interaction between silica sols and surfactants, including rod-type or egg-type structure. To combine thiol or amine group with the surface of silica particles, 3-mercaptopropyl trimethoxysilane (MPTMS) or 3-aminopropyl trimethoxysilane (APTMS) were used. All samples exhibited characteristic Type II BET isotherms, consistent with non-porous materials. The structure and functionality of these materials were characterized by field-emission scanning electron microscopy, fourier transform infrared spectroscopy, nitrogen adsorption and desorption, optical microscopy, and Energy-dispersive X-ray.