CAREER: Synthesis and Characterization of Metal/Silica Multicomponent Classes by the Sol-Gel Process

摘要9623570 Stiegman本研究的两个主要目标是推进影响溶胶-凝胶法制备和加工多元玻璃的化学参数的研究，并制备和表征全新的金属/硅多元玻璃。将开展三项主要工作：1.新型金属/二氧化硅干凝胶的合成。利用为氧钒材料建立的合成方案，几个金属和金属中心官能团将被结合到二氧化硅干凝胶基质中。这项工作的核心是优化条件，以确保每种金属的均质性。选择纳入的金属将基于它们预期的反应性和它们作为一系列系统变化的材料的一部分的位置，以阐明结构-性质关系。2.阐明了多组分条件下溶胶-凝胶过程的化学过程。这将涉及确定金属对胶凝的动力学和机制、老化、干燥和稳定过程的影响。这将使我们从根本上理解当存在许多动力学上不同的组分时，在溶胶-凝胶过程中发生的化学过程。3.新型多元玻璃的性质和反应性的表征。杂化材料的表征将包括两个主要活动：(1)表征二氧化硅基质中金属中心的配位几何和电子结构；(2)表征块状干凝胶的物理和形态性质。由不同比例的金属氧化物和半金属氧化物组成的均质多组分玻璃，由于其多样的和潜在的有用的性质和反应活性而引起了人们的极大关注。预计这些材料的应用包括多相催化剂、化学传感器和环境监测器，以及光学和电子元件。虽然溶胶-凝胶法已经成功地用于制备特定的材料，但问题阻碍了它作为一种制备均匀混合玻璃的方法的普遍使用。这些问题是由于各种成分的凝胶化动力学差异很大，以及与这些材料的老化和干燥相关的许多变量引起的；所有这些都可能导致最终产品的异质性。这项工作的目的是优化生产均匀玻璃所需的条件，并提供关于金属/二氧化硅混合玻璃的形成和性能的详细和全面的图景，以便为将这类材料引入实际应用领域做出重大贡献。

Abstract 9623570 Stiegman The two principal goals of this research are to advance study of the chemical parameters that effect the synthesis and processing of multicomponent glasses by the sol-gel process, and to fabricate and characterize entirely new metal/silica multicomponent glasses. Three primary activities will be conducted: 1. The synthesis of new metal/silica xerogels. Several metal and metal-centered functional groups will be incorporated into the silica xerogel matrix using the synthetic protocol established for the oxovanadium materials. Central to this effort is the optimization of conditions to insure homogeneity for each metal. The metals chosen for incorporation will be based on their anticipated reactivity and on their position as part of a series of systematically varying materials for the elucidation of structure-property relationships. 2. Elucidation of the chemistry of the sol-gel process under multicomponent conditions. This will involve determining the effects of the metal on the kinetics and mechanism of gelation, the processes of aging, drying and stabilization. This will provide a fundamental understanding of the chemical processes that occur in the solgel process when many kinetically different components are present. 3. Characterization of the properties and reactivity of the new multicomponent glasses. The characterization of the hybrid materials will entail two primary activities: (1) characterization of the coordination geometry and electronic structure of the metal center as it is found in the silica matrix; and (2) characterization of the physical and morphological properties of the bulk xerogel. %%% Homogeneous multicomponent glasses, comprised of differing ratios of metal and semimetal oxides, have attracted considerable attention due to their diverse and potentially useful properties and reactivities. Among the applications predicted for these materials are as heterogeneous catalysts, chemical sensors and environmental monitors, and optical and electronics components. While the sol-gel process has been used successfully to prepare specific materials, problems have precluded its general employment as a method for preparing homogeneous hybrid glasses. These problems arise from the widely differing gelation kinetics of the various constituents and by the many variables associated with aging and drying these materials; all of which can lead to heterogeneity in the final product. The aim of this work is to optimize the conditions needed to produce a homogeneous glass, and provide a detailed and comprehensive picture of the formation and properties of hybrid metal/silica glasses to contribute significantly to bringing this class of materials into the sphere of real applications.