Fabrication of Helical Mesoporous Silica Tubes with Confined Assembly Process

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0855322 FangThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Helical mesoporous silica is attractive because of its potential applications in chiral catalysis and separations, which are of great interest in the pharmaceutical industry. The objective of this proposed research is to fabricate helical mesoporous silica tubes by the confined assembly of achiral surfactants and tetraethoxysilane (TEOS) inside chiral lipid tubules. The specific aims required to achieve the objective are summarized as follows: (1) synthesize chiral lipid tubules with varying handedness, pitches, diameters and surface charge, (2) fabricate right and left-handed helical mesoporous silica tubes by the confined assembly of achiral surfactants and TEOS inside the chiral lipid tubules of L- and D-enentiomers, (3) alter the pitches of helical mesoporous silica tubes by the confined assembly of achiral surfactants and TEOS inside the chiral lipid tubules with varying helical pitches, (4) change the diameter of helical mesoporous silica tubes by the confined assembly of achiral surfactants and TEOS inside the chiral lipid tubules with different diameters, and (5) correlate the surface charge of chiral lipid tubules with the morphology, helicity, and pore architectures of templated helical mesoporous silica tubes. Intellectual Merit: Chirality plays an important role in biology. By introducing chiral elements into mesoporous silica, new structures and properties can be achieved. Self-assembled chiral lipid tubules provide a unique confinement to assemble achiral surfactants and silica precursors into helical mesoporous silica tubes. The fabrication of single-handed helical mesoporous silica tubes with controllable diameters, handedness, pitches, and pore architectures is particular interested in chiral catalysis and separations. The silica tubes with helical mesoporous walls represent a new hierarchical tubular structure. Three different kinds of surfaces (the out surface, the inner surface of the central tubular cavity, and the mesoporous internal surface of helical walls) may be functionalized differently or act together in helical mesoporous silica tube-integrated chemical systems. The interconnection between the cavity and the mesopores makes helical mesoporous silica tubes attractive for practical applications due to increased capabilities of mass transport. Broad Impacts: A detailed understanding of how the chiral confinement affects the morphologies, sizes, helicity, and pore architectures of templated helical mesoporous silica materials will provide an insight into the mechanism of governing the confined assembly and lead to better design principles in utilizing helical mesoporous silica materials in chiral catalysis and separations. Graduate and undergraduate students, who are involved in this proposed research, will be trained in the interdisciplinary field of materials chemistry, materials processing, and nanotechnology. The outreach activities through NSF Florida Georgia Louis Stokes Alliance for Minorities Participation in Engineering and the Orlando Science Center program will promote the participation of underrepresented groups and high school seniors, which will benefit the broad community. The integration of the proposed research will involve graduate students, undergraduates, and minorities in scientific research and discovery, which is essential for the next generation of scientists and engineers.