Infrared method for in situ studies of polymer/surfactant adsorption on silica powders from aqueous solution

This article presents a general infrared spectroscopic method that enables the monitoring of the adsorption of surfactants and polyelectrolytes on high surface area silica particles from aqueous solution. The method is based on the use of a ZnSe internal reflection element (IRE) coated with a layer of titania particles. The titania surface is then converted to silica using atomic layer deposition with sequential addition of an amine catalyst, gaseous SiCl4, and water vapor. A minimum of three cycles is needed to produce a surface that mimics silica, as evidenced by the reaction of hexamethyidisilazane and zeta potential measurements. It is shown that the silica-coated titania particles on the ZnSe crystals are stable to flowing aqueous solutions below pH = 8 and can be used to study the dynamics of polymer/surfactant adsorption on silica.