High Efficiency Nanoparticulate Emulsifiers

美国国家科学基金会-化学运输系统司？微粒多相工艺程序（1415）提案编号：0729967主要研究者：Tilton，Robert附属机构： 卡内基梅隆大学提案题目：高效纳米颗粒乳化剂。由吸附在油/水界面处的胶体颗粒稳定的乳液，通常称为皮克林乳液，其特征在于它们对聚结和沉降的上级稳定性以及它们分散高不连续相体积分数的能力。我们建议开发具有极高乳化效率的新型纳米颗粒乳化剂。原子转移自由基聚合（ATRP）将用于创建纳米颗粒接枝的两亲性共聚物刷，其具有良好控制的结构，旨在驱动颗粒以高亲和力吸附并稳定油/水界面。我们将制备两类纳米颗粒乳化剂。第一种类型具有二氧化硅核，其表面接枝有共聚物两亲物。第二种类型是多臂杂臂星星聚合物，其具有被两种或多种类型的延伸臂包围的致密聚合物核。这些接枝的刷状颗粒具有比常规颗粒乳化剂更多的自由度，这可以允许更精细地调节界面热力学和机械性质。当颗粒吸附到油/水界面时，两亲性刷的构象将适应局部溶剂环境。在开发最有效的乳化剂时，将确定刷结构和乳化之间的潜在机械关系。主要的技术目标是所提出的纳米颗粒接枝刷以稳定乳液，其浓度至少比当前颗粒乳化剂所需的浓度小十倍。所提出的结构中的一些可以是热响应的，以响应于温度线索而去热响应。更广泛的影响。拟议的工作将形成化学工程博士的跨学科培训。学生和化学博士的一部分。学生的训练。两人都将接受功能材料的设计和物理表征以及最先进的受控自由基聚合技术的培训。一个中学外展计划将开发界面工程的主题，其中公立学校的科学教师花一个或两个夏天在PI的实验室开发学生实验室模块和课程计划的界面在自然和材料的作用。将有一个日常材料的主题，涉及植物油/水皮克林乳液和？新奇？主题，建立在粒子稳定界面的科学，以了解如何所谓的？液体弹珠（Aussillous，P.; Quearea，D.，Nature 2001，411，924-927）工作。PI将提供界面热力学的要点，并帮助教师准备关于毛细作用力及其在自然界中发生的教案。PI随后将作为嘉宾加入教师的课堂。这项研究将提供共聚接枝颗粒乳化剂，为乳化效率设定标志，以及满足任何依赖乳液的行业（农业，食品，个人护理？）新应用所需的刷子设计原则。通过对颗粒乳化剂的显著改进，新的应用可能成为可能。例如，柴油乳液比常规柴油燃料燃烧更清洁，并且乳化剂配方是一个主要挑战。

National Science Foundation - Division of Chemical &Transport Systems ? Particulate & Multiphase Processes Program (1415)Proposal Number: 0729967Principal Investigators: Tilton, RobertAffiliation: Carnegie Mellon University Proposal Title: High Efficiency Nanoparticulate EmulsifiersIntellectual Merit. Emulsions stabilized by colloidal particles adsorbed at the oil/water interface, commonly called Pickering emulsions, are distinguished by their superior stability against coalescence and sedimentation and by their ability to disperse high discontinuous phase volume fractions. We propose to develop novel nanoparticulate emulsifiers with extremely high emulsification efficiency. Atom transfer radical polymerization (ATRP) will be used to create nanoparticle-grafted, amphiphilic copolymer brushes with well-controlled architectures designed to drive particles to adsorb with high affinity and stabilize the oil/water interface. We will prepare two categories of nanoparticulate emulsifiers. The first type has a silica core with copolymer amphiphiles grafted from or to its surface. The second type are multi-arm miktoarm star polymers with dense polymer cores surrounded by two or more types of extended arms. These grafted brush particles have more degrees of freedom than conventional particulate emulsifiers that may allow for finer tuning of interfacial thermodynamic and mechanical properties. The conformation of the amphiphilic brushes will adapt to the local solvent environment as particles adsorb to the oil/water interface. In developing the most effective emulsifiers, the underlying mechanistic relationships between brush architecture and emulsification will be determined. The main technological goal is for the proposed nanoparticle-grafted brushes to stabilize emulsions at concentrations at least ten times smaller than are required for current particulate emulsifiers. Some of the proposed structures may be thermally responsive to de-emulsify in response to temperature cues. Broader Impact. The proposed work will form the interdisciplinary training of a Chemical Engineering Ph.D. student and for part of a Chemistry Ph.D. student's training. Both will be trained in the design and physical characterization of functional materials as well as state-of-the-art controlled radical polymerization techniques. A secondary school outreach program will be developed on themes of interfacial engineering, whereby public school science teachers spend one or two summer months in the PI's lab to develop student lab modules and lesson plans on the role of interfaces in nature and materials. There will be an everyday materials theme involving vegetable oil/water Pickering emulsions and a ?novelties? theme that builds on the science of particle-stabilized interfaces to understand how so-called ?liquid marbles? (Aussillous, P.; Quearea, D., Nature 2001, 411, 924-927) work. The PI will provide the essentials of interfacial thermodynamics and help the teacher prepare lesson plans on capillary forces and their occurrence in nature. The PI will subsequently join the teacher as a guest in the classroom. This research will deliver copolymer-grafted particulate emulsifiers that set the mark for emulsification efficiency, together with the brush design principles needed to meet new applications in any industry that relies on emulsions (agriculture, foods, personal care?). New applications may be made possible by significant improvements in particulate emulsifiers. For example, diesel emulsions combust more cleanly than conventional diesel fuel, and emulsifier formulation is a major challenge.