Hierarchical Biosilicates by the 3-D Replication of Block Copolymer Templates in Supercritical Fluids

摘要

Unique methods for the encapsulation of biologically-derived materials within ordered mesoporous silica films, the preparation of mesoporous silica films using a biodegradable template system, and the preparation of thermally stable, mesoporous silica spheres with tunable diameters ranging from 40 nm to 560 nm, narrow size distributions on the order of 10%, surface areas greater than 1000 m2/g, and pore volumes on the order of 1 cc/g were demonstrated. The stable spheres were synthesized using tetraethylorthosilicate at room temperature and near-neutral pH using cysteamine as the catalyst and cetyltrimethylammonium bromide (CTAB) as the structure directing agent in a mixed water and ethanol system. The pore walls were resistant to collapse at temperatures exceeding 750-deg C in air and upon hydrothermal treatment in boiling water for over 100 hours. Silica formed using bio-inspired small molecule catalysts including cysteamine, glutathione and methionine alone or in combination provided highly condensed silica networks at room temperature over a broad range of pH as evidenced by 29Si NMR.