UNS: Mechanisms of Surface Charging in Nonpolar Media

CBET -1511619 PI：Schneider，James许多具有技术重要性的产品都涉及液体中的颗粒悬浮液。 本计画探讨浸入非极性液体中的粒子电荷形成的机制。 在颗粒上形成电荷可以在颗粒之间产生静电排斥，从而抑制它们的聚集，这导致稳定的悬浮液。 某些类型的表面活性剂可以作为带电剂添加到悬浮液中，以帮助静电稳定悬浮液。 PI开发了一种合成分子结构具有系统变化的表面活性剂系列的方法。 这些表面活性剂的表面充电特性的特点是使用两种仪器开发的合作PI。 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、印刷用油基墨粉和缓释肥料。 研究人员将以电子阅读器为例，让K-12学生学习显示技术的基础科学，并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其稳定颗粒的倾向，解决长期存在的关于非极性溶剂中电荷形成的问题。该合成技术提供了对尾长、支化程度、头基化学和反式组成的完全控制。将使用ZetaSpin方法在受控化学的测试表面上测量表面充电，该方法在测量期间进行zeta电位测量而无需考虑颗粒絮凝。粒子间电位将通过高灵敏度的TIRM方法测量。 阐明粒子间的潜力将确定如果古伊-查普曼理论或反离子唯一的理论是一个有效的描述在不同的系统中的电荷屏蔽效应。相应的衰变长度将给出比从电导率测量获得的离子强度更可靠的测量。这个项目将提供有价值的深入了解充电化合物的合理设计，并将有助于发展新的理论来描述掺杂的非极性粒子间的潜力。

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.