The Kinetics of Phase Stability in Periodic Silica/Surfactant Nanostructured Materials

周期性二氧化硅/表面活性剂纳米结构材料的相稳定性动力学

• 批准号: 9807180
• 负责人: Sarah Tolbert
• 金额: $ 27.09万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-01 至 2002-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9807180&HistoricalAwards=false
• 关键词: Kinetics; Phase; Stability; Periodic; Silica

9807180TolbertThis project involves experiments which directly probe the thermodynamic and kinetic factors controlling stability in ordered silica/surfactant mesostructured composites. These exciting new materials consist of an organized organic component, which controls long range periodicity, and an inorganic framework, which provides stability and strength. Importantly, the organic component can be removed to produce ordered mesoporous materials which have potential for a wide range of applications. Kinetic phenomena appear to play a major role in the formation of these materials and thus understanding these kinetic effects would be enormously useful for the rational design of future materials. Phase transitions in these materials will be followed in real time to gain insight into the driving forces and kinetic factors controlling structure. Two classes of experiments are envisioned: The first set involves structural changes under hydrothermal conditions in response to thermal and chemical treatments. By systematically varying the organic moieties and the degree of silica framework polymerization, transition kinetics reveal the interplay between organic packing and the rigid inorganic silica framework. Real-time X-ray scattering and solid-state NMR spectroscopy will be utilized to follow structural change and to learn about the evolution of both long range periodicity and local bonding. The second set of experiments directly probe the role of packing constraints by examining phase behavior under high pressure. Here, the ability of these composites to reorganize under non-hydrothermal conditions will be determined. These experiments offer hope for separating the role of surfactant packing from that of silica polymerization.%%%Addressing the kinetics of phase stability in periodic silica/surfactant nanostructured materials will provide information that can be directly used to synthesize new classes of silica/surfactant composites, with the goal of learning how to kinetically trap or thermodynamically favor new composite or mesoporous structures for specific applications in catalysis, separations, or chemical sensing.***

9807180TOLBERTTHIS项目涉及实验，这些实验直接探测有序二氧化硅/表面活性剂介质化复合材料中控制稳定性的热力学和动力学因子。 这些令人兴奋的新材料由有组织的有机成分组成，该组件控制远程周期性和无机框架，可提供稳定性和强度。 重要的是，可以去除有机成分以生产有序的中孔材料，这些材料具有广泛应用的潜力。 动力学现象似乎在这些材料的形成中起主要作用，因此理解这些动力学效应对于未来材料的合理设计非常有用。 这些材料中的相转换将进行实时遵循，以深入了解驱动力和动力学因素控制结构。设想了两类实验：第一组涉及在热液条件下响应热和化学处理的结构变化。 通过系统地改变有机部分和二氧化硅框架聚合的程度，过渡动力学揭示了有机堆​​积与刚性无机二氧化硅框架之间的相互作用。实时X射线散射和固态NMR光谱将用于遵循结构变化，并了解远程周期性和局部键合的演变。 第二组实验直接通过检查高压下的相行为来直接探测填料约束的作用。 在这里，将确定这些复合材料在非热热条件下重组的能力。 这些实验提供了希望将表面活性剂填料与二氧化硅聚合分开的作用。%%%处理定期二氧化硅/表面活性剂纳米结构材料的相位稳定性动力学，这些信息将直接用于合成新的二氧化硅/表面活性剂的新类别的靶标或对Kinody -Kinetmanticallys traps trap的靶心，以综合新类别。在催化，分离或化学传感中。***