UNS: Mechanisms of Surface Charging in Nonpolar Media

CBET-1511619PI：施耐德，詹姆斯许多具有技术重要性的产品涉及液体中颗粒的悬浮。这个项目研究了浸泡在非极性液体中的粒子的电荷形成机制。颗粒上电荷的形成会在颗粒之间产生静电斥力，从而抑制颗粒的聚集，从而导致稳定的悬浮液。某些类型的表面活性剂可以作为荷电剂添加到悬浮液中，以帮助稳定悬浮液的静电。PI已经开发出一种方法来合成分子结构具有系统变化的表面活性剂集合。这些表面活性剂的表面电荷特性将使用由co-PIs开发的两种仪器来表征。该项目的结果将有助于检验非极性介质中的荷电理论，并最终导致合理设计用于非极性介质中荷电和颗粒稳定的改进表面活性物质。这样的系统在各种技术中都很重要，包括电子阅读器、印刷用油基碳粉和缓释化肥。研究人员将使用电子阅读器的例子来吸引K-12学生学习基础显示技术的基础科学，并将开发一个用于大学生教学的模块。该项目旨在通过创建高纯度、定制合成的表面活性剂库并研究它们稳定粒子的倾向来解决长期存在的关于非极性溶剂中电荷形成的问题。这种合成技术可以完全控制尾长、支化程度、头基化学和反离子组成。表面电荷将在受控化学的测试表面上使用ZetaSpin方法进行测量，该方法使Zeta电位测量无需考虑测量过程中的颗粒絮凝。粒间势将用高灵敏的TIRM方法测量。粒子间势的阐明将决定Gouy-Chapman理论或仅反离子理论是不同系统中电荷屏蔽效应的有效描述符。与电导率测量相比，相应的衰变长度将给出更可靠的离子强度测量。该项目将为电荷化合物的合理设计提供有价值的见解，并将有助于发展新的理论来描述掺杂非极性粒子间的势。

CBET - 1511619PI: Schneider, JamesMany products of technological importance involve suspensions of particles in liquids. This project examines the mechanisms of electrical charge formation on particles immersed in nonpolar liquids. The formation of charges on particles can create electrostatic repulsions between the particles that inhibit their aggregation, which leads to a stable suspension. Certain types of surfactants can be added to the suspension as charging agents to help stabilize the suspension electrostatically. The PI has developed a method to synthesize collections of surfactants with systematic variations in their molecular structures. The surface charging characteristics of these surfactants will be characterized by using two instruments developed by the co-PIs. Results of the project will help test theories of charging in nonpolar media and ultimately lead to the rational design of improved surfactant materials for charging and particle stabilization in nonpolars. Such systems are important in a variety of technologies, including e-readers, oil-based toners for printing, and slow-release fertilizers. The researchers will use the example of the e-reader to engage K-12 students in the basic science underlying display technology and will develop a module for use in university student instruction.This project aims to resolve long-standing questions concerning charge formation in nonpolar solvents by creating libraries of high-purity, custom-synthesized surfactants and studying their propensity to stabilize particles. The synthesis technique gives full control of tail length, extent of branching, headgroup chemistry, and counterion composition. Surface charging will be measured on test surfaces of controlled chemistry using the ZetaSpin method, which makes zeta potential measurements without concern for particle flocculation during the measurement. Inter-particle potentials will be measured by the highly sensitive TIRM method. Elucidation of interparticle potentials will determine if the Gouy-Chapman theory or the counterion-only theory is a valid descriptor of charge screening effects in different systems. The corresponding decay lengths will give a more reliable measure of ionic strength than can be obtained from conductivity measurements. This project will provide valuable insight into the rational design of charging compounds and will help develop new theories to describe inter-particle potentials in doped nonpolars.