Collaborative Research: New Routes for the Preparation and Characterization of Functionally-Graded and Mesoporous Silica Thin Films

丹尼尔教授A.堪萨斯州立大学的希金斯和玛丽安娜M.弗吉尼亚联邦大学的Collinson博士在分析和表面化学项目的支持下，探索新型介孔膜的合成和性质。制备薄膜和表面结合组成梯度是当代科学感兴趣的主题。 这样的“功能梯度”材料结合梯度的极性，孔隙率和离子位点密度具有潜在的应用作为固定相分离，作为吸收剂/吸附剂层用于化学或生物传感器，并作为一种手段来调节细胞的表面粘附，以指导神经元的生长，甚至驱动液体的运输。 在这项合作提案中，正在研究一种独特的方法，用于使用溶胶-凝胶化学和当代电化学沉积技术来创建二氧化硅薄膜，该薄膜具有厚度，孔隙率和组成的梯度。 这些材料固有的复杂性和可变性激发了使用单分子成像和光谱（SMS）来获得纳米级和分子水平的详细信息。将开发SMS方法，以获得关于孔径和微环境极性沿梯度沿着变化的信息。 除了这些新的功能梯度材料，介孔材料，表现出可逆的收缩响应于干燥或溶液性质的变化也将在单孔水平和特征。 表现出可逆收缩和膨胀的材料对于污染物的捕获和隔离以及药物、农药和肥料的受控释放是潜在有用的。 新的单分子荧光共振能量转移（FRET）方法将用于监测这些材料的孔径变化与纳米级的灵敏度。 在堪萨斯州和弗吉尼亚联邦参与这项研究的学生将获得合成，材料科学和单分子光谱学方面的广泛经验。参与本研究的所有参与者将受益于该计划提供的全面教育，通过每周网络会议和定期实地访问合作实验室分享知识，数据和材料。

Professor Daniel A. Higgins of Kansas State University and Professor Maryanne M. Collinson of Virginia Commonwealth University are supported by the Analytical and Surface Chemistry Program to explore the synthesis and properties of novel mesoporous films. The preparation of films and surfaces incorporating compositional gradients is a topic of contemporary scientific interest. Such "functionally graded" materials incorporating gradients in polarity, porosity, and ionic site density have potential applications as stationary phases for separations, as absorbent/adsorbent layers for use in chemical or biological sensors, and as a means to regulate surface adhesion of cells, to direct the growth of neurons, and even to drive the transport of liquids. In this collaborative proposal, a unique approach is being studied for creating silica films that incorporate gradients in thickness, porosity, and composition using sol-gel chemistry and contemporary electrochemical deposition techniques. The inherent complexity and the variable nature of these materials inspired the use of single molecule imaging and spectroscopy (SMS) to obtain detailed information at the nanoscale and molecular level. SMS methods will be developed to obtain information on variations in pore size and microenvironment polarity along the gradients. In addition to these new functionally graded materials, mesoporous materials that exhibit reversible shrinkage in response to drying or changes in solution properties will also be made and characterized at the single pore level. Materials that exhibit reversible shrinking and expansion are potentially useful for the capture and sequestration of pollutants and for the controlled release of drugs, pesticides and fertilizers. Novel single-molecule fluorescence resonance energy transfer (FRET) methods will be used to monitor pore size variations in these materials with nanometer-scale sensitivity. Students participating in this research at Kansas State and Virginia Commonwealth will receive an unusually broad experience in synthesis, materials science and single molecule spectroscopy. All the participants involved in this research will benefit from the comprehensive education provided by this program via the sharing of knowledge, data and materials in weekly web conferences and periodic site visits to the collaborating laboratories.