Optically-Driven Changes in Nanoparticle Solvation, Transport and Interaction

液体中的分子在固体表面附近以一系列不同的方式组织起来，这种现象称为溶剂化。该组织在重要的物理过程和技术中发挥着核心作用。 例如，溶剂化是使用液体作为润滑剂以最小化两个表面之间的摩擦或控制金属（例如金）纳米颗粒组装成用于传感的先进材料的基础。溶剂化在确定固液界面性质中的核心作用激发了许多过去旨在改变溶剂化的努力。 过去的努力包括向液体中添加盐或控制温度和压力。 这个项目超越了过去的研究，通过调查使用可见光来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容易地操纵，因此该方法具有使溶剂化的可逆和主动控制成为可能的潜力。 这项研究的成功结果可能为新的节能分离过程或为低成本传感器网络创建材料的新方法提供基础。本计画将阐明奈米粒子的光激发如何改变其溶剂化、输运性质及相行为。 研究的第一个推力集中在单个纳米粒子，并阐明了纳米粒子的光激发如何改变界面溶剂结构，从而改变纳米粒子的流体动力学尺寸。研究的第二个重点是研究纳米粒子溶剂化的光诱导变化如何改变成对相互作用，包括双电层和溶剂结构的贡献。 测量纳米粒子对的概率距离分布函数将被倒置以获得平均力的势。 研究的第三个重点是研究纳米粒子溶剂化的光学驱动变化如何影响集体现象，例如纳米粒子分散体的稳定性及其相分离。 该研究计划的总体成果将是对纳米粒子溶剂化过程中光学驱动变化所产生的基本传输和相分离过程的新知识。该奖项反映了NSF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.