Growth of Mesoporous Silica Film with Vertical Channels on Substrate Using Gemini Surfactants

摘要

The mesoporous silica thin films have attracted extreme interests in recent years because of their potential applications as sensors, optoelectronic devices, and functional membranes. Such films with lamellar, hexagonal, and cubic mesostruc-tures can be formed at solid/liquid/vapor interfaces by spin-/ dip-coating methods. In general, these films are expected to have a three-dimensional (3D) or two-dimensional (2D) mesostructure with mesochannels normal to the substrate. It then makes great sense to fabricate films that have highly ordered structures and high porosity, yet are mechanically strong and allow selective but free transportation of materials through the films. Mesoporous silica films with 3D structures were synthesized under the direction of gemini surfactants in acidic conditions. However, most prevailing 2D-hexagonal mesostructures are usually composed of parallel-oriented channels. For obtaining films with 2D vertical mesochannels, some complicated strategies and special conditions were applied in previous works, which included nano-phase separation of eutectic materials, microphase separation of block copolymers, surface modification for confinement effects, employment of electric and magnetic fields, electrochemical assistance, introduction of ternary surfactant systems, and π—π interaction of template molecules. However, the synthesis of mesoporous silica films with macroscopic 2D vertical channels is still full of challenges.