Fabrication of Helical Mesoporous Silica Tubes with Confined Assembly Process

0855322方该奖项由2009年美国复苏和再投资法案(公共法律第111-5条)资助。螺旋介孔二氧化硅因其在手性催化和分离方面的潜在应用而颇具吸引力，这在制药行业引起了极大的兴趣。本研究的目的是通过非手性表面活性剂和正硅酸乙酯(TEOS)在手性脂小管中的受限组装来制备螺旋介孔二氧化硅管。实现这一目标所需要的具体目标概括如下：(1)合成不同手性、螺距、直径和表面电荷的手性脂管；(2)通过手性表面活性剂和正硅酸乙酯在L-和D-分子手性脂管内的受限组装来制备右旋和左旋螺旋介孔二氧化硅管；(3)通过在不同螺距的手性脂管内约束非手性表面活性剂和正硅酸乙酯的组装来改变螺旋介孔二氧化硅管的间距；(4)通过在不同直径、不同螺距的手性脂管内约束手性表面活性剂和正硅酸乙酯的组装来改变螺旋介孔二氧化硅管的直径(5)手性脂管的表面电荷与模板化螺旋介孔二氧化硅管的形态、螺旋度和孔结构之间的关系。智力价值：手性在生物学中扮演着重要的角色。通过在介孔二氧化硅中引入手性元素，可以获得新的结构和性能。自组装的手性脂质管为将非手性表面活性剂和二氧化硅前驱体组装成螺旋介孔二氧化硅管提供了独特的限制条件。单手螺旋介孔二氧化硅管的制备具有可控的直径、手性、间距和孔道结构，是手性催化和分离领域的研究热点。具有螺旋介孔壁的二氧化硅管代表了一种新的层次化管状结构。在螺旋介孔二氧化硅管集成化学体系中，三种不同的表面(中心管腔的外表面、中心管腔的内表面和螺旋壁的介孔内表面)可以不同地功能化或共同作用。空腔和介孔之间的相互连接使螺旋介孔二氧化硅管具有更强的传质能力，因此在实际应用中具有很大的吸引力。广泛的影响：详细了解手性限制如何影响模板化螺旋介孔二氧化硅材料的形貌、大小、螺旋度和孔结构，将有助于深入了解限制组装的机制，并在利用螺旋介孔二氧化硅材料进行手性催化和分离方面得出更好的设计原则。参与这项拟议研究的研究生和本科生将接受材料化学、材料加工和纳米技术等跨学科领域的培训。通过美国国家科学基金会、佛罗里达州、佐治亚州、路易斯·斯托克斯少数族裔参与工程学联盟和奥兰多科学中心计划开展的外联活动将促进代表不足的群体和高中生的参与，这将使广大社区受益。拟议的研究将包括研究生、本科生和少数族裔参与科学研究和发现，这对下一代科学家和工程师至关重要。

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.