Surface Forces at Electrified Interfaces

带电界面的表面力

• 批准号: 9907687
• 负责人: T. Kyle Vanderlick
• 金额: $ 32.4万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9907687&HistoricalAwards=false
• 关键词: Surface; Forces; Electrified; Interfaces

CTS-9907687T.K. VanderlickPrinceton UniversitySummaryThe aim of this proposal is to use direct force measurements to investigate the structure and properties of electrified interfaces. Such interfaces are, of course, of premier importance in the far-reaching and significant field of electrochemistry. In addition, however, electrochemical based forces play significant roles in biology (e.g. establishing the conformation and function of biomolecules), in physical chemistry (e.g., swelling of clays), in engineering (e.g., stabilization of colloids and emulsions), and in many industrial processes.While the electrode/electrode interface is one of the most complex solid/liquid interfaces, its structure can be effectively interrogated through the measurement of surface forces. Such interrogations can take advantage of the range and strength of electrostatic interactions, as well as the ability to modify interactions by changing the applied potential to the electrochemically active surfaces. Forces acting between surfaces reflect the structural details of the surfaces themselves as well as that of the medium trapped between them.The primary tool for the proposed investigations is an "electrochemical surface forces apparatus." This new device extends the unique capabilities of the surface forces apparatus to systems in which one, or both, interacting surfaces is metallic and under applied potential control. The proposed work is divided along three themes providing opportunities for a range of significant scientific and technological advances.The first theme of research is to use force profiling to elucidate the basic structure of electrode/electrolyte interfaces. The objective is to measure, as a function of separation, the forces of interaction between surfaces where one, or both, are typical electrode materials, namely gold (Au), silver (Ag) or platinum (Pt). Forces will be measured as a function of the potential applied to the surfaces and also the nature of the electrolyte. The role of specific adsorption of anions will be explicitly investigated. The most basic experiment will involve interactions between molecularly smooth mica and one electrochemically active surface, acting as a working electrode. Specific objectives include establishing the potential of zero charge for the various electrochemical systems; testing DLVO predictions for interactions between dissimilar surfaces; establishing the limits of application of DLVO theory, and probing the short-range structure of electrode/electrolyte interfaces.The second theme of research is to study the adhesion and associated deformations of electrified surfaces. The framework of contact mechanics will be used to study the loading and unloading behavior of electrified surfaces under potential control. One system of investigation will be mica in contact with gold. The electrochemical nature of gold surfaces (three distinct potential regimes: Au/AuOH/AuO) provides a rich foundation for these investigations.The third theme of research focuses on a variety of electrode modifications schemes for selective and active control of surface forces. The goal is to demonstrate how certain molecular adsorbates or coating formed on electrodes can serve to alter their interactions with other surfaces in useful and novel ways. Systems for study include ionizable self-assembled monolayers which respond to pH changes; self-assembled monolayers that release attached molecules when electrical potentials are applied the underlying metal substrate; and adsorbed surfactant monolayers which undergo structural changes with applied potential. Alteration of electrode surfaces by underpotential deposition of metals will be also examined.

CTS-9907687 T.K. VanderlickPrinceton UniversitySummaryThe目的是使用直接力测量来研究带电界面的结构和性质。 当然，这种界面在电化学的深远和重要领域中具有首要重要性。 然而，此外，基于电化学的力在生物学（例如建立生物分子的构象和功能）、物理化学（例如，粘土的溶胀），在工程中（例如，虽然电极/电极界面是最复杂的固/液界面之一，但其结构可以通过测量表面力来有效地询问。 这样的询问可以利用静电相互作用的范围和强度，以及通过改变施加到电化学活性表面的电势来修改相互作用的能力。 作用在表面之间的力反映了表面本身的结构细节，以及被困在它们之间的介质的结构细节。“这种新装置将表面力装置的独特能力扩展到其中一个或两个相互作用的表面是金属的并处于施加的电势控制下的系统。 拟议的工作分为沿着三个主题提供了一系列重大的科学和技术进步的机会。第一个主题的研究是使用力剖面阐明电极/电解质界面的基本结构。 目的是测量作为分离函数的表面之间的相互作用力，其中一个或两个表面是典型的电极材料，即金（Au）、银（Ag）或铂（Pt）。 力将作为施加到表面的电势以及电解质的性质的函数来测量。 将明确研究阴离子的特异性吸附的作用。 最基本的实验将涉及分子光滑云母和一个电化学活性表面之间的相互作用，作为工作电极。 具体目标包括建立各种电化学系统的零电荷电位;测试DLVO预测不同表面之间的相互作用;建立DLVO理论的应用范围，并探测电极/电解质界面的短程结构。研究的第二个主题是研究带电表面的粘附和相关变形。 在接触力学的框架下研究电位控制下带电表面的加载和卸载行为。 一种研究体系将是与金接触的云母。 金表面的电化学性质（三个不同的电位制度：Au/AuOH/AuO）为这些调查提供了丰富的基础。研究的第三个主题集中在各种电极修饰计划的选择性和主动控制的表面力。 目的是证明某些分子吸附物或电极上形成的涂层如何以有用和新颖的方式改变它们与其他表面的相互作用。 用于研究的系统包括响应pH变化的可电离的自组装单分子层;当电势施加到下面的金属基底时释放附着分子的自组装单分子层;以及随着施加的电势而经历结构变化的吸附的表面活性剂单分子层。 还将研究由金属的欠电位沉积引起的电极表面的改变。