Accessibility of dye molecules embedded in surfactant-silica hybrid materials in both powder and film forms

Two CTABr-silica mesophases have been prepared, one of them as a powder with hexagonal structure containing Congo Red, the other one as a film with cubic structure containing Disperse Red 1. In the former case the dye has been occluded via co-entrapping, whereas in the latter it has been covalently anchored to the silica matrix via a co-condensation route. In both systems, the dye molecules proved to be accessible to NH3 and HCl in gas phase, notwithstanding the presence of micelles in the mesophase, which results to be fully permeable to such molecules.