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Nanoscale Interdisciplinary Research Team:
Tailored Fluorinated Surfactants for Templating of Ordered Nanoporous Ceramics
Introduction
Control over pore size and shape is essential to the development of new and improved materials for many applications including catalysis, chemical separations, chemical and biochemical sensing, photonics, and electronic materials. Ceramic materials synthesis at or near room temperature provide many exciting opportunities to control pore geometry. In this project, we use liquid-phase reactions of alkoxysilane precursors to generate silica in the presence of surfactants. The temperature is in the range (between 0 and 110 °C) where the growing silicates and surfactants spontaneously self-assemble to form ordered aggregates (see the Figure below). The solidification of the ceramic permanently traps a structure analogous to the lyotropic liquid crystalline phases formed by surfactants and block copolymers at high concentration. The ceramic (tetrahedra in the Figure) occupies the part of the liquid crystal normally occupied by a polar solvent. After the solid is formed, the surfactant (with yellow tails and blue heads) is removed to generate nanoscale pores. Organic functionality (represented in red in the Figure) can be incorporated by using organically modified silanes as part of the synthesis solution.
Control over pore size and shape is essential to the development of new and improved materials for many applications including catalysis, chemical separations, chemical and biochemical sensing, photonics, and electronic materials. Ceramic materials synthesis at or near room temperature provide many exciting opportunities to control pore geometry. In this project, we use liquid-phase reactions of alkoxysilane precursors to generate silica in the presence of surfactants. The temperature is in the range (between 0 and 110 °C) where the growing silicates and surfactants spontaneously self-assemble to form ordered aggregates (see the Figure below). The solidification of the ceramic permanently traps a structure analogous to the lyotropic liquid crystalline phases formed by surfactants and block copolymers at high concentration. The ceramic (tetrahedra in the Figure) occupies the part of the liquid crystal normally occupied by a polar solvent. After the solid is formed, the surfactant (with yellow tails and blue heads) is removed to generate nanoscale pores. Organic functionality (represented in red in the Figure) can be incorporated by using organically modified silanes as part of the synthesis solution.
