Controlling Nanocomposite Properties by Nanoparticle Assembly

聚合物纳米复合材料是聚合物材料和纳米尺寸无机颗粒的混合物，人们对聚合物纳米复合材料一直很感兴趣，主要是因为它们相对于相应的纯聚合物提供了显著改善的物理性能的承诺。虽然迄今为止已经有许多关于这些主题的研究，但很少有人从与控制纳米颗粒（NP）分散体相关的科学细节到优化出现的实际相关的热和机械性能。这个研究项目的三个方面都侧重于以一种对应用程序有直接影响的方式建立这种联系。(i)拟议的研究压力的影响将描绘的作用，加工在聚合物/NP混合物和这种变化的分散状态的性质的后果。 (ii)在第二个线程中，本研究将研究NP形状对优化热性能和机械性能的作用。 (iii)最后，所提出的研究的实际后果将探讨取代化学附着的聚合物分子的纳米粒子的物理连接的。这些战略是否等同，如果不是，它们在哪些具体方面不同？这些研究工作将与一系列教育和外联活动相结合。该组织最近的活动包括招募高中和本科生进行夏季研究，该提案将继续招募历史上少数民族学校（如佛罗里达A M）的学生，以及来自大纽约市环境的本科生和高中生（和教师）。PI的团队之前曾与几名女性和少数民族高中生合作，他们随后在大学学习科学和工程，并将继续这种管道方法走向科学和工程职业。技术总结：人们对聚合物纳米复合材料一直感兴趣，主要是因为这些混合物相对于纯聚合物提供了显着的性能改进的承诺。虽然迄今为止已经有许多关于这一主题的研究，但很少有人从控制纳米颗粒（NP）分散状态到优化出现的热机械性能。提出的整体方法，结合实验和理论，重点正是弥合这一差距（a）研究的基本原理的组装过程及其后果的性质，（B）移植不断发展的理解，使其更适合应用。本论文的主要研究内容有以下三个方面：（1）严格研究压力在聚合物/NP混合物中的作用。高压可以用来控制NP的分散吗？它对性能有什么影响？ (ii)同样，该研究将探索NP形状作为进一步优化热机械性能的途径的作用。 (iii)最后，所提出的研究的实际后果将研究取代化学接枝链上的纳米粒子的物理吸附链。这个想法是否可行，在改善物业方面有何利弊？这些研究活动与广泛的教育和外联活动相结合。由该集团最近的活动，涉及高中和本科生的夏季研究，并与该集团的发达互动与佛罗里达A M大学（HBCU），该提案是继续招募代表性不足的学生（包括妇女和少数民族）在高中，本科和研究生水平的一部分，该集团的研究工作。PI还与纽约城市学院的化学工程系合作，将大纽约地区的学者（教师和学生），当地工业和国家实验室聚集在一起，举办年度化学工程研讨会。我们的目标是，不仅要把毕业的学生到当地的行业，而且要吸引工业参与者到更高的学位和/或进修课程在哥伦比亚。

NON-TECHNICAL SUMMARY:There has been continuing interest in polymer nanocomposites, which are mixtures of polymeric materials and nanometer-sized inorganic particles, primarily because they offer the promise of significantly improved physical properties relative to the corresponding pure polymer. While there have been many studies on these topics to date, very few have gone from the scientific details relevant to controlling the nanoparticle (NP) dispersions to optimizing the practically relevant thermal and mechanical properties that emerge. Each of the three prongs of this research project focuses on establishing this connection in a way that has a direct impact on applications. (i) The proposed research on pressure effects will delineate the role of processing in homogenizing polymer/NP mixtures and the consequences of this changing dispersion state on properties. (ii) In a second thread, this research will study the role of NP shape on optimizing thermal and mechanical properties. (iii) Finally, the practical consequences of the proposed research will be explored by replacing chemically attached polymer molecules on the NPs by the physically attached ones. Are these strategies equivalent, and, if not, in what tangible ways are they different?These research efforts will be coupled to a suite of education and outreach activities. Driven by the group's recent activities involving recruiting high school and undergraduate students for summer research, the proposal is to continue to recruit students from historically minority schools (such as Florida A&M), as well as undergraduate and high school students (and teachers) from the greater New York City environment. The PI's group has previously worked with several women and minority high-school students who have subsequently gone on to study science and engineering in college, and will continue this pipeline approach toward science and engineering careers.TECHNICAL SUMMARY:There has been continuing interest in polymer nanocomposites, primarily because these hybrids offer the promise of significant property improvements relative to the pure polymer. While there have been many studies on this topic to date, very few of them have gone all the way from controlling the nanoparticle (NP) dispersion state to optimizing the thermomechanical properties that emerge. The overall approach proposed, which combines experiments and theory, focuses precisely on bridging this gap by (a) studying the fundamentals of the assembly process and its consequences on properties, and (b) porting the evolving understanding to make it more amenable to applications. The proposed research has the following three prongs: (i) Critically studying the role of pressure in homogenizing polymer/NP mixtures. Can high pressure be used to control NP dispersion and what are its effects on properties? (ii) Similarly, the research will explore the role of NP shape as a route to further optimizing thermomechanical properties. (iii) Finally, the practical consequences of the proposed research will be studied by replacing chemically-grafted chains on the NPs by the physical adsorption of chains. Is this idea feasible and what are its advantages and disadvantages in terms of property improvements?These research activities are coupled to extensive education and outreach activities. Driven by the group's recent activities involving high school and undergraduate students for summer research, and with the group's well-developed interactions with Florida A&M University (an HBCU), the proposal is to continue to recruit underrepresented students (both women and minorities) at the high school, undergraduate and graduate levels to be part of the group's research efforts. The PI is also working with the Chemical Engineering department at the City College of New York to bring together academics in the Greater New York area (faculty and students), local industry and national laboratories in an annual chemical engineering symposium. The goal is, not only to place graduating students into local industry, but also to attract industrial participants into higher degree and/or refresher programs at Columbia.