Optically-Driven Changes in Nanoparticle Solvation, Transport and Interaction

液体中的分子在靠近固体表面的地方以各种不同的方式组织起来，这种现象被称为溶剂化。这个组织在重要的物理过程和技术中起着中心作用。例如，溶剂化是使用液体作为润滑剂的基础，以尽量减少两个表面之间的摩擦，或控制金属纳米粒子（例如金）组装成先进的传感材料。溶剂化在决定固液界面性质方面的核心作用激发了许多过去旨在改变溶剂化的努力。过去的努力包括在液体中添加盐或控制温度和压力。该项目超越了以往的研究，通过研究可见光的光学激发和改变金属表面的溶剂化。光传递到系统的强度和位置可以很容易地操纵，因此该方法有可能实现可逆和主动的溶剂化控制。这项研究的成功结果可能为新的节能分离工艺或为低成本传感器网络创造材料的新方法提供基础。该项目将阐明光激发如何改变纳米颗粒的溶剂化、输运性质和相行为。研究的第一个重点是单个纳米颗粒，并阐明了纳米颗粒的光激发如何改变界面溶剂结构，从而改变纳米颗粒的水动力尺寸。研究的第二个重点是探讨纳米颗粒溶剂化中光学诱导的变化如何改变成对相互作用，包括电双层和溶剂结构的贡献。对纳米粒子对的概率距离分布函数的测量将被反转，以获得平均力的势。研究的第三个重点是研究光学驱动的纳米颗粒溶剂化变化如何影响集体现象，如纳米颗粒分散的稳定性及其相分离。这项研究计划的总体成果将是对纳米颗粒溶剂化中光学驱动变化引起的基本输运和相分离过程的新知识。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Molecules within liquids organize themselves near solid surfaces in a range of different ways, a phenomenon called solvation. This organization plays a central role in important physical processes and technologies. For example, solvation underlies the use of liquids as lubricants to minimize friction between two surfaces or to control the assembly of nanoparticles of metals (for example, gold) into advanced materials for sensing. The central role of solvation in determining the properties of solid-liquid interfaces has motivated many past efforts aimed at changing solvation. Past efforts have included addition of salts to liquids or manipulation of temperature and pressure. This project moves beyond past studies by investigating the use of visible light to optically excite and change solvation of metal surfaces. The intensity and location at which light is delivered to a system can be readily manipulated, and thus the approach has the potential to make possible reversible and active control of solvation. The successful outcome of this research may provide the basis of new energy-efficient separations processes or new ways to create materials for low-cost sensor networks. This project will elucidate how optical excitation of nanoparticles can change their solvation, transport properties and phase behavior. The first thrust of research focuses on single nanoparticles, and elucidates how optical excitation of nanoparticles changes interfacial solvent structuring and thus nanoparticle hydrodynamic size. The second thrust of research examines how optically-induced changes in nanoparticle solvation alter pair-wise interactions, including electrical double layer and solvent-structural contributions. Measurements of probability distance distribution functions for pairs of nanoparticles will be inverted to obtain potentials of mean force. The third thrust of research investigates how optically-driven changes in nanoparticle solvation influence collective phenomena, such as the stability of dispersions of nanoparticles and their phase separation. The overall outcome of this program of research will be new knowledge of fundamental transport and phase separation processes arising from optically-driven changes in nanoparticle solvation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.