Colloidal Micromechanics and Near-Contact Interactions

胶体微观力学和近接触相互作用

• 批准号: 0500321
• 负责人: Eric Furst
• 金额: $ 4万
• 依托单位: University of Delaware
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-15 至 2007-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0500321&HistoricalAwards=false
• 关键词: Colloidal; Micromechanics; Near; Contact; Interactions

ABSTRACT - 0500321University of DelawareWe propose to investigate the micromechanical response and near-contact interactions that underlie the properties of colloidal gels. This will be accomplished using novel experiments we have developed based on optical trapping, which enables us to directly assemble model aggregates from individual colloids and controllably deform them while measuring microscopic stresses. The proposed work will build on the preliminary results obtained under an exploratory grant (NSF CTS-0209936), in which we demonstrated and measured tangential interactions between colloids that arise in near-contact regimes. Our work quantified, for the first time, the single-bond bending rigidity between particles, and discovered regimes of linear and non-linear bending mechanics of aggregates. These properties have dependences on physico-chemical conditions, such as the solution ionic strength and adsorption of surfactants. The mechanics to be studied, unrecognized until now, have considerable consequences for the processing and properties of particulate gels, because of their influence on the yield stress, aging properties and moduli of these materials. The activity proposed here will build upon the successes of two years of exploratory funding, and will significantly extend this activity to develop new experiments based on insights we have gained. In addition, we will work with research groups from other universities who will bring expertise in modeling heterogeneous colloidal interactions and particle characterization via AFM. Expecting that this work will have a significant technological impacts, we have positioned ourselves for productive industrial collaborations and contacts within the DuPont Automotive Coatings Division.Intellectual Merit. Because particulate gels occur in a wide variety of manufacturing processes, including coatings, pharmaceutical formulations, ceramic parts manufacturing, mineral recovery and lubricant degradation, there is considerable interest in the ability to predict and control their properties. Gelation also adversely affects efforts to crystallize proteins, limiting the characterization of protein structure and function. Although there have been notable advances in recent years, the fundamental mechanisms of the mechanical and rheological properties of particulate gels based on interparticle interactions, microstructure and micromechanics have yet to be fully understood. By spanning the nano- and micro-scale physics to macroscopic behavior, we will establish the fundamentals needed to synthesize new materials, and improve the prediction and control of product and processing properties in existing materials. Furthermore, the understanding and control of colloidal interactions that are a natural aspect of this work, extends beyond gel rheology to novel and emerging applications, such as photonic crystals, chembiosensors and nanotechnology. The lack of experimental methods capable of examining near-contact interactions between nonideal colloidal surfaces has been cited as an area in critical need of development, which we are well-equipped to address.Broader Impacts. This work will provide education and research training for two graduate students in the technologically-critical field of colloid science. This training experience will be significantly enhanced through our interactions with groups at Yale Unviersity and DuPont Marshall Labortory. Funds will support one undergraduate research student to complete an Honors thesis. To date, this work has had a significant educational impact, resulting in one MChE (currently a matriculated Ph.D. student), three undergraduate honors theses (co-authors on two papers in preparation) and, currently, one senior thesis student, who is expected to co-author two upcoming papers. Results of this research will reach a broad community of scientists and engineers through publications in journals and presentations at national and international scientific meetings.

摘要 - 0500321特拉华大学我们建议研究胶体凝胶特性背后的微机械响应和近接触相互作用。这将通过我们基于光学捕获开发的新颖实验来完成，这使我们能够直接从单个胶体组装模型聚集体，并在测量微观应力的同时可控地使它们变形。拟议的工作将建立在探索性资助（NSF CTS-0209936）下获得的初步结果的基础上，其中我们演示并测量了近接触状态下出现的胶体之间的切向相互作用。我们的工作首次量化了颗粒之间的单键弯曲刚度，并发现了聚集体的线性和非线性弯曲力学机制。这些特性取决于物理化学条件，例如溶液离子强度和表面活性剂的吸附。迄今为止尚未认识到的待研究力学对颗粒凝胶的加工和性能具有相当大的影响，因为它们对这些材料的屈服应力、老化性能和模量有影响。 这里提出的活动将建立在两年探索性资助的成功基础上，并将显着扩展这项活动，以根据我们获得的见解开发新的实验。此外，我们将与其他大学的研究小组合作，他们将带来通过 AFM 模拟异质胶体相互作用和颗粒表征的专业知识。 预计这项工作将产生重大的技术影响，我们已在杜邦汽车涂料部门内进行富有成效的工业合作和联系。智力优势。由于颗粒凝胶存在于各种制造过程中，包括涂料、药物配方、陶瓷零件制造、矿物回收和润滑剂降解，因此人们对预测和控制其特性的能力非常感兴趣。凝胶化还会对蛋白质结晶产生不利影响，限制蛋白质结构和功能的表征。尽管近年来取得了显着的进展，但基于颗粒间相互作用、微观结构和微观力学的颗粒凝胶的机械和流变性能的基本机制尚未完全了解。 通过跨越纳米和微观物理到宏观行为，我们将建立合成新材料所需的基础知识，并改进对现有材料的产品和加工性能的预测和控制。此外，对胶体相互作用的理解和控制是这项工作的一个自然方面，它超越了凝胶流变学，扩展到新颖和新兴的应用，例如光子晶体、化学生物传感器和纳米技术。 缺乏能够检查非理想胶体表面之间近接触相互作用的实验方法被认为是一个急需发展的领域，我们有能力解决这个问题。更广泛的影响。这项工作将为胶体科学技术关键领域的两名研究生提供教育和研究培训。通过我们与耶鲁大学和杜邦马歇尔实验室的团队的互动，这种培训经验将得到显着增强。资金将支持一名本科生完成荣誉论文。迄今为止，这项工作已经产生了重大的教育影响，产生了一名 MChE（目前是一名已被录取的博士生）、三篇本科荣誉论文（两篇论文正在准备中的合著者）以及目前的一名高级论文学生，预计他将与人共同撰写两篇即将发表的论文。这项研究的结果将通过期刊上的出版物以及在国家和国际科学会议上的演讲，传播给广大科学家和工程师。