Pickering Emulsions - A Paradigm Shift

摘要-0500323德州理工大学乳状液普遍存在于自然和工业过程中。传统的乳液使用有机表面活性剂或聚合物作为稳定剂。固体颗粒稳定乳状液(Pickering乳状液)虽然在原油回收、原油分离净化、废水处理等方面经常遇到，但近一个世纪以来，人们对这一现象知之甚少，一直被忽视。迫切需要新的专家来满足我国在这一研究领域的需要。这项建议侧重于以皮克林乳剂为中心的研究和教育的整合。使用激光扫描共聚焦显微镜和环境透射电子显微镜(ETEM)将研究微米和纳米固体颗粒在Pickering乳剂中的自组装。对于含有微粒子的Pickering乳液，我们将研究固体粒子浓度、粒子大小、粒子润湿性和本体粘度对自组装的影响。我们还将测试朗缪尔吸附模型的适用性。对于含有纳米颗粒的Pickering乳剂，我们将研究纳米颗粒的结构(单层或多层，有序或随机堆积等)。并将实验结果与微观非连续介质模型进行比较。此外，我们还将研究微粒在乳状液界面上的迁移率，特别是界面曲率对单粒子运动和多粒子团簇迁移率的影响。Pickering乳状液提供了一种新的胶体科学范式，所提出的工作有望有助于更好地从根本上理解Pickering乳状液的形成。由于Pickering乳液为固体颗粒的自组装提供了一种新颖而简单的模板，因此拟议的工作也有助于揭示固体颗粒在液/液界面自组装的潜在机制。Pickering乳状液还可以作为模型系统来研究固体颗粒在两个维度上的扩散、迁移率和原位结构形成。此外，PI小组的初步工作提供了使用电子显微镜技术在液体介质中成像纳米颗粒的第一项工作，以及当纳米颗粒的尺寸与液体的分子尺寸相当时，揭示在液/液界面上自组装纳米颗粒的详细结构的第一项工作。使用电子显微镜技术的后续研究将对纳米粒子科学和技术产生重大影响。更广泛的影响(外在优点)研究和教育之间的整合将被实施，以满足NSF的战略成果目标：人、想法和工具。由于对教育的坚定承诺，PI将在现有课程中建立与研究相关的开放式项目，促进本科和研究生研究，建立一个新的暑期计划，以扩大代表不足的群体的参与，指导大学预科工程学院，并促进技术转让。Pickering乳液涉及粒子使用的创新概念；拟议的工作预计将为广泛的实际应用提供新的机会，并将成为以促进经济增长和提高生活质量的方式将智力资本和新兴技术结合在一起的杰出例子。预计它还将对石油开采产生重大影响，这将对环境恢复和保护做出重大贡献。最后，但并非最不重要的是，该项目还提供了一个独特的机会，以满足我国对尖端研究的迫切需求，该研究在21世纪具有令人难以置信的扩展潜力。

ABSTRACT - 0500323Texas Tech UniversityEmulsions are ubiquitous in natural and industrial processes. Conventional emulsions use organic surfactants or polymers as stabilizers. Although solid particle stabilized emulsions (Pickering emulsions) are often encountered in the recovery of crude oil, oil separation and cleaning, and wastewater treatment, the phenomenon is poorly understood and has been neglected for nearly a century. There is a critical call for new experts to meet our nation's need in this research area.This proposal focuses on integrating research and education centering on Pickering emulsions. Self-assembly of micro-sized and nano-sized solid particles in Pickering emulsions will be investigated using a laser scanning co focal microscope and an environmental transmission electron microscope (ETEM). For Pickering emulsions containing microparticles, we will investigate the influence of solid particle concentration, particle size, particle wettability, and bulk viscosity on self-assembly. We will also test the applicability of the Langmuir adsorption model. For Pickering emulsions containing nanoparticles, we will investigate the structure of nanoparticles (monolayer or multilayer, ordered or randomly packed, etc.) at the emulsion interface and compare experimental results to a microscopic noncontinuum model. In addition, we will investigate the mobility of microparticles at emulsion interfaces, in particular the influence of interface curvature on the single particle movement and the mobility of multi-particle clusters.Pickering emulsions offer a new paradigm of colloidal science, and the proposed work is anticipated to contribute significantly to a better fundamental understanding of the formation of Pickering emulsions. The proposed work also contributes to the underlying mechanisms of the self assembly of solid particles at liquid/liquid interfaces since Pickering emulsions offer a novel and simple template for self-assembling solid particulates. Pickering emulsions can also serve as model systems to investigate diffusion, mobility, and in-situ structural formation of solid particles at the two dimension. In addition, the preliminary work from the PI's group offers the first work of imaging nanoparticles in a liquid medium using the ETEM technique, as well as the first work revealing the detailed structure of self-assembled nanoparticles at a liquid/liquid interface when the size of the nanoparticles is comparable to the molecular dimension of the liquids. Follow-up research using the ETEM technique will have a significant impact on nanoparticle science and technology.Broader Impacts (Extrinsic Merit) The integration between research and education will be performed to meet the NSF's goals for strategic outcomes: People, Ideas and Tools. With a strong commitment to education, the PI will establish research-related open-ended projects in the existing courses, promote undergraduate and graduate research, establish a new summer program to broaden the participation of underrepresented groups, mentor in the Pre-College Engineering Academy, and promote technology transfer. Pickering emulsions involve an innovative concept for particle use; the proposed work is anticipated to provide new opportunities for widespread practical applications and will be an outstanding example of bringing intellectual capital and emerging technologies together in ways that promote economic growth and an improved quality of life. It is also anticipated to make a meaningful impact in oil recovery, which will contribute significantly to environmental restoration and protection. Last, but not least, this project also provides a unique opportunity to meet our nation's critical need for a cutting-edge research with a potential of incredible expansion in the 21st century.