UNS: Mechanisms of Surface Charging in Nonpolar Media

[参考译文]许多重要的技术产品都涉及液体中的颗粒悬浮液。本项目研究浸入非极性液体中粒子的电荷形成机制。粒子上电荷的形成可以在粒子之间产生静电斥力，从而抑制它们的聚集，从而导致稳定的悬浮。某些类型的表面活性剂可以作为充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具有分子结构系统变化的表面活性剂集合。这些表面活性剂的表面充电特性将用两种仪器来表征。该项目的结果将有助于测试非极性介质中的充电理论，并最终导致改进的表面活性剂材料的合理设计，用于非极性介质中的充电和颗粒稳定。这种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肥料。研究人员将以电子阅读器为例，让K-12年级的学生了解显示技术的基础科学，并将开发一个模块，用于大学生教学。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，解决长期存在的关于非极性溶剂中电荷形成的问题。该合成技术可以完全控制尾长度、分支程度、头基化学和反离子组成。使用ZetaSpin方法在受控化学的测试表面上测量表面电荷，该方法使zeta电位测量无需考虑测量过程中的颗粒絮凝。粒子间电位将通过高灵敏度的TIRM方法测量。粒子间势的阐明将决定gay - chapman理论或纯反理论是否是不同体系中电荷筛选效应的有效描述。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。该项目将为带电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物质的粒子间势。

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.