Collaborative Research: Characterization of Functionally-Graded Sol-Gel-Derived Silica Films on Multiple Length Scales, from Single Molecules to Macroscopic Properties

合作研究：功能梯度溶胶-凝胶衍生二氧化硅薄膜在多个长度尺度上的表征，从单分子到宏观性能

• 批准号: 1404805
• 负责人: Daniel Higgins
• 金额: $ 28万
• 依托单位: Kansas State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1404805&HistoricalAwards=false
• 关键词: Collaborative; Research; Characterization; Functionally; Graded

Non-Technical AbstractThe development of new materials for advanced technologies usually requires that a large number of different samples be synthesized and tested one by one to find those best suited for the intended application. An alternative to this often-tedious process is to produce a material incorporating a chemical gradient in which the composition gradually varies along a single sample. The speed at which optimum new materials are developed and identified is thus greatly enhanced. These rapid-throughput-screening applications of chemical gradients find possible utility in the development of better catalysts for production of pharmaceuticals, plastics, lubricants and fuels and in the fabrication of surfaces with adhesion properties tailored for the attachment and growth of biological tissues. Chemical gradients also find direct utility in the separation of specific components from complex chemical mixtures and in guiding the delivery of liquids, chemical precursors and cells in miniaturized chemical devices and sensors. For all such applications, the gradients to be employed must have well defined chemical and physical properties. Ideally, they would exhibit gradual, monotonic compositional and properties variations extending from the macroscale down to molecule levels. In reality, such idyllic character seldom exists. Unexpected properties variations may arise from the spontaneous separation of the gradient components during preparation, producing materials that exhibit stepwise rather than gradual properties variations, and limit the participation of often-desirable cooperative interactions. These attributes make gradient materials uniquely more complex and valuable than either single component materials or uniform nongradient films prepared from identical precursors. This activity emphasizes exploration of the chemical and physical complexity of organosilane gradients prepared by novel wet-chemical methods recently developed by the principal investigator's groups. The outcomes will lead to development of gradients having better understood and better controlled properties that can be more effectively implemented in advanced materials. The synergy between the collaborating groups will lead to the enhanced training of a diverse body of undergraduate and graduate students in state-of-the-art materials synthesis and their characterization by advanced chemical imaging methods. These students will be actively mentored by both investigators and will participate in a summer exchange program between the two campuses and weekly web conferences to broaden their educational, scientific and career horizons. Technical AbstractWith the support from the Solid State and Materials Chemistry Program in the Division of Material Research, the principal investigators will (1) investigate the extent to which phase separation and synergistic interactions occur along multicomponent organosilane gradients prepared by the sol-gel process and (2) evaluate the sizes and compositions of the resulting domains. Materials to be investigated will include multicomponent polarity, acidity, charge and dopant gradients derived from different organoalkoxysilane precursors. Over the long term, the impacts of nanometer-to-micrometer scale phase separation and cooperative interactions on the macroscopic properties of these gradients will be explored. Gradient composition will be characterized on multiple length scales (micrometer-to-millimeter) by x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and Raman mapping. All three will yield quantitative data on the distance scales over which gradient composition varies and will allow for the chemical origins of any cooperative effects to be fully understood. Single molecule superlocalization microscopy will be used to probe the gradients on nanometer length scales and to elucidate cooperative interactions between the gradient components themselves as well as between a probe molecule and the film components. Quantitative data on materials polarity will be obtained through implementation of unique single molecule level measurements of the local dielectric constant of the films. In all cases, results from the gradients will be compared to those from uniform nongradient samples.

非技术摘要的高级技术新材料的开发通常要求将大量不同的样本合成并一一测试，以找到最适合预期应用的样本。 这种经常谨慎的过程的一种替代方法是产生一种结合化学梯度的材料，其中该成分逐渐沿单个样品变化。因此，开发和确定最佳新材料的速度大大提高。 这些化学梯度的这些快速通量筛查的应用可能在开发更好的催化剂时可能实用，以生产药品，塑料，润滑剂和燃料，以及制造具有针对生物组织附着和生长的粘附特性的表面制造。 化学梯度还可以在从复杂的化学混合物中分离特定组件的分离以及指导小型化学设备和传感器中的液体，化学前体和细胞的递送时找到直接效用。 对于所有这些应用，要使用的梯度必须具有明确定义的化学和物理性能。 理想情况下，它们将表现出从宏观下向下延伸到分子水平的渐进，单调组成和特性变化。 实际上，这种田园诗很少存在。出乎意料的特性变化可能是由于制备过程中梯度成分的自发分离，产生逐步表现出的材料而不是逐渐的特性变化，并限制了经常可取的合作相互作用的参与。 这些属性使梯度材料比单一组件材料或由相同前体制备的单一组件材料或均匀的非剂膜更为复杂和有价值。这项活动强调了通过主要研究者群体最近开发的新型湿化学方法制备的有机硅烷梯度的化学和物理复杂性的探索。结果将导致具有更好理解和更好地控制特性的梯度的发展，这些阶级可以在高级材料中更有效地实施。 协作小组之间的协同作用将导致对最先进材料合成的本科生和研究生的多样化培训，并通过先进的化学成像方法进行表征。 这些学生将受到调查人员的积极指导，并将参加两个校园和每周网络会议之间的夏季交流计划，以扩大其教育，科学和职业视野。技术摘要与固态和材料化学计划的支持在材料研究部中，首席研究人员将（1）研究沿SOL-GEL过程制备的多组分有机硅烷梯度发生的相位分离和协同相互作用的程度，以及（2）评估所得域的大小和组成。要研究的材料将包括多组分极性，酸度，电荷和掺杂剂梯度，这些梯度来自不同的有机烷氧基硅烷前体。 从长远来看，将探讨纳米到微米计尺度相位分离和合作相互作用对这些梯度的宏观特性的影响。梯度组成将通过X射线光电子光谱，傅立叶变换红外光谱和拉曼映射在多个长度尺度（微米至毫米）上进行表征。 这三个都将在梯度组成变化的距离尺度上产生定量数据，并允许对任何合作效应的化学起源充分理解。单分子超定位显微镜将用于探测纳米长度尺度上的梯度，并阐明梯度成分本身以及探针分子与膜成分之间的合作相互作用。材料极性的定量数据将通过实施膜的局部介电常数的独特单分子水平测量。 在所有情况下，将梯度的结果与均匀非ad剂样品的结果进行比较。