(473a) Responsive and Controlled Release of Surfactants from Porous Tubular Silica Nanoparticles for Improved Interfacial Properties

Silica nanoparticles (NPs) have attracted widespread attention from researchers in many different areas. This is due to the simple synthesis and functionalization of their surfaces, and the fact that they are environmentally compatible for many applications. However, unmodified silica NPs are hydrophilic, which limits their potential uses especially for interfacial control due to the weak adsorption to a hydrophobic-hydrophilic interface. In this presentation we describe an innovative approach to improve the interfacial properties of silica NPs to improve their adsorption at the oil-water interface. The approach is based on encapsulating cationic surfactants into tubular porous silica nanoparticles that have a diameter of 50-100 nm and are 200 nm long. The release of surfactants is accomplished by reverse ion exchange made possible by the abundance of ions in the suspension. The improved interfacial properties were quantified by dynamic interfacial measurements as well as static contact angle experiments. The potential use of the proposed system ranges from wettability modification to improved emulsion stability.