Mesoporous silica from reverse lyotropic liquid crystals: A novel approach

We report on the preparation and characterization of mesoporous silica monoliths by a new method based on the templating of reverse lyotropic liquid crystals formed in a polydimethylsiloxane-graft-polyoxyethylene copolymer. The silica formation mechanism involves strong interaction between the PDMS chains and the silicate species. The as-prepared monoliths show thermally switchable transparency, attributed to the presence of hydrophilic nanodomains. The calcined materials contain a hexagonal array of mesopores (diameter = 40–50 Å) with very thick walls (thickness = 50–60 Å), showing little shrinkage upon calcination. Moreover, they are thermally stable and apparently have reduced microporosity as compared to other mesoporous materials prepared from nonionic amphiphiles. A new mechanism is proposed for the preparation of these mesoporous materials, which offer new possibilities for interesting applications.