Insights of the kolliphor/water system for the design of mesostructured silica materials

Abstract

Abstract Herein, mesostructured silica materials have been prepared through the Cooperative Templating Mechanism (CTM) using kolliphor EL (KEL) as biocompatible surfactant. First, the behavior of KEL in water has been studied and the phase diagram has been determined. KEL forms micelles (L1) in water and in higher concentrations a liquid crystal domain appears, which is constituted of a cubic phase (Pm3n) and a direct hexagonal phase. Small Angle X-ray Scattering (SAXS) experiments were performed to study the structure of the Organized Molecular Systems. We show that KEL leads to spherical micelles in water, which have a radius comprised between 6.2 and 6.5 nm, depending on the surfactant concentration. Then, mesoporous materials were synthesized and characterized by SAXS measurements and nitrogen adsorption-desorption analysis. The structure of the recovered material is affected by the surfactant/silica molar ratio. Indeed, the mesopore ordering is detected only for ratios in the range between 0.017 and 0.031. As long as mesostructures are obtained, the mesopores diameters are in accordance with the dimension of the hydrophobic size of the micelles.