Fabrication of Helical Mesoporous Silica Tubes with Confined Assembly Process

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。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受到人们的广泛关注。本研究的目的是利用非手性表面活性剂和四乙氧基硅烷（TEOS）在手性脂质小管内的密闭组装制备螺旋介孔硅管。实现这一目标所需的具体目标总结如下：(1)合成具有不同手性、节距、直径和表面电荷的手性脂管；(2)在L-和d -对映体的手性脂管内，通过非手性表面活性剂和TEOS的限制性组装，制备了左右螺旋介孔硅管；(3)在具有不同螺旋节距的手性脂管内，通过非手性表面活性剂和TEOS的限制性组装，改变了螺旋介孔硅管的节距。(4)通过非手性表面活性剂和正硅酸乙酯在不同直径的手性脂质管内的密闭组装，改变螺旋介孔硅管的直径；(5)将手性脂质管的表面电荷与模板化的螺旋介孔硅管的形态、螺旋度和孔结构联系起来。智力优势：手性在生物学中起着重要作用。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。自组装手性脂质管提供了一个独特的限制组装非手性表面活性剂和二氧化硅前体成螺旋介孔二氧化硅管。单手螺旋介孔硅管具有可控制的直径，手性，节距和孔结构，尤其对手性催化和分离感兴趣。具有螺旋介孔壁的硅管代表了一种新的分层管状结构。三种不同的表面（外表面、中心管腔的内表面和螺旋壁的介孔内表面）可能在螺旋介孔硅管集成化学系统中被不同地功能化或共同作用。空腔和介孔之间的相互连接使得螺旋介孔硅管在实际应用中具有吸引力，因为它增加了质量传输的能力。广泛影响：详细了解手性约束如何影响模板化螺旋介孔二氧化硅材料的形态、大小、螺旋度和孔隙结构，将有助于深入了解控制受限组装的机制，并为利用螺旋介孔二氧化硅材料进行手性催化和分离提供更好的设计原则。参与这项研究的研究生和本科生将在材料化学、材料加工和纳米技术等跨学科领域接受培训。通过美国国家科学基金会佛罗里达乔治亚路易斯斯托克斯少数族裔参与工程联盟和奥兰多科学中心项目开展的外展活动将促进代表性不足的群体和高中毕业生的参与，这将使广大社区受益。拟议研究的整合将涉及研究生，本科生和少数民族的科学研究和发现，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.