UNS: Mechanisms of Surface Charging in Nonpolar Media

CBET - 1511619PI：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。 该项目研究了浸没在非极性液体中的颗粒上电荷形成的机制。 颗粒上电荷的形成可以在颗粒之间产生静电排斥力，从而抑制它们的聚集，从而形成稳定的悬浮液。 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 开发了一种合成分子结构具有系统变化的表面活性剂集合的方法。 这些表面活性剂的表面充电特性将通过使用共同PI开发的两种仪器来表征。 该项目的结果将有助于测试非极性介质中的充电理论，并最终合理设计用于非极性介质中充电和颗粒稳定的改进表面活性剂材料。此类系统在多种技术中都很重要，包括电子阅读器、印刷用油基碳粉和缓释肥料。 研究人员将利用电子阅读器的例子让 K-12 学生了解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其稳定颗粒的倾向，解决有关非极性溶剂中电荷形成的长期问题。该合成技术可以完全控制尾部长度、支化程度、头基化学和抗衡离子组成。将使用 ZetaSpin 方法在受控化学的测试表面上测量表面电荷，该方法可进行 zeta 电位测量，而无需担心测量过程中的颗粒絮凝。颗粒间电势将通过高灵敏度 TIRM 方法进行测量。 粒子间电势的阐明将确定古伊-查普曼理论或仅抗衡离子理论是否是不同系统中电荷屏蔽效应的有效描述。相应的衰减长度将给出比从电导率测量获得的更可靠的离子强度测量值。该项目将为带电化合物的合理设计提供有价值的见解，并将有助于开发描述掺杂非极性粒子间电势的新理论。

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.