Continuous Formation of Supported Unusual Mesostructured Silica Films by Sol−Gel Dip Coating

Abstract

Novel silicone surfactant was first used as the template to prepare mesostructured silica films with unusual lamellar structure. Complex mesostructured silica films can be obtained using the mixture of silicone surfactantand cetyltrimethylammonium bromide (C 1 6 TAB: CH 3 (CH 2 ) 1 5 N + (CH 3 ) 3 Br - ) as the surfactant in conjunction with the sol-gel dip-coating process. The results show that silicone surfactants favor the formation of lamellar structure. Highly ordered long-range lamellar structure has the largest lattice constant known for lamellar materials to date reported. Moreover, the hexagonal mesophase can be easily created in layered silica walls just by adding C 1 6 TAB in the silicone surfactant templating system. The lamellar mesophase and the hexagonal mesoporosity in the walls were separately templated from silicone-based surfactant and C 1 6 TAB in the mixed surfactant templating systems, and thus hierarchically ordered silica formed. The examples presented supply strong evidence that oxide mesophases are governed by supramolecular chain configuration; i.e., unrestricted chain configuration (Si-O-Si chain in silicone surfactant) is responsible for the formation of the zero-curvature lamellar silica mesophase and restrictive chain configuration (C-C-C chain in C 1 6 TAB) for the high-curvature hexagonal mesophase, even their existing in a one-pot system.