Nanoparticles as Surfactants: Static and Dynamic Properties

0932259 Leal“该奖项是根据2009年美国复苏和再投资法案(公共法律111-5)资助的。”共聚物和聚合物功能化纳米粒子在多相聚合物系统中的界面活性具有深刻的科学意义和巨大的工业重要性。除了它们提出的各种基础科学问题外，这些合成相容剂还可以混合不相容的聚合物。此外，功能化纳米颗粒的核心材料可以提供额外的化学或物理功能(磁、光、热或电子)。然而，即使是对它们是如何工作的基本理解也仍然缺乏。本研究的目的是测量、预测和模拟纳米粒子和共聚表面活性剂的静态和动态性质。如果没有这样的能力进行这样的测量，从而对它们的操作有一个基本的了解，那么为先进的聚合物共混物合理设计合成相容剂仍然是不可能的。拟议项目的核心智力价值是开发和应用新技术来测量和了解合成共聚聚合物和纳米粒子“表面活性剂”在聚合物/聚合物界面上的静态和动态性质，这基本上是第一次。这需要实现三个具体目标：(1)开发新的微尺度技术和工具。将开发两种新的新技术：微张力计和主动微观流变学技术，用于测量相容剂负载界面的表面粘弹性和非线性粘度；(2)使用这些新工具来测量和表征纳米粒子和共聚表面活性剂的静力学和动力学。具体地说，我们将测量纳米粒子和共聚表面活性剂的表面压力与浓度等温线、表面活性剂扩散系数和界面粘弹性，它们的性质将以系统和全面的方式改变；以及(3)开发理论，捕捉测量的行为并进行可测试的预测；从而推广我们的结果，使人们对这些合成相容剂的作用机理有一个直观的了解，并指导设计规则。这项拟议的工作具有潜在的高度变革性：它不仅提出了开发新的和前所未有的测量能力，而且还提出了对共聚物和纳米颗粒表面活性剂的静态和动态行为的基本和一般理解，以及如何设计它们的直觉。拟议工作的更广泛影响是相当大的。首先，将要开发的测量工具只需要微量的样品，但将能够控制界面组成以及测量界面张力和流变性，这将是史无前例的。就所提供的信息而言，拟议工作的这一方面将具有真正的变革性。这些具体的测量将是此类测量中的第一次，并将为从根本上了解纳米粒子表面活性剂在聚合物/聚合物界面上的静态和动态性质迈出第一步。这样的理解也将具有潜在的变革性，因为它将使具有所需性能的先进聚合物材料的合理设计和加工成为可能。这些团体将继续利用UCSB材料研究实验室的全国认可的外展基础设施，在暑期和学年研究项目中积极招聘和指导有代表性的少数族裔学生和总体上雄心勃勃的本科生。一名高中教师将参与暑期研究，以影响他/她自己的经历以及他/她的学生在未来几年的生活。为了接触更广泛的大学社区，将为非理科学生开发一门新的研讨会课程，内容是日常生活中常见的流变学有趣产品的科学和工程，包括食品和个人护理产品。这个想法是为了让学生接触到有趣的、无处不在的、令人惊讶地可以理解的材料世界，这些材料既不是固体也不是液体。作为本课程的一部分，调查人员将在网上免费发布讲稿和演示视频；在成功开发后，我们将为化学工程教育撰写一篇描述性文章，以鼓励和促进其他本科或高中课程的相关课程内容。

0932259Leal"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."The interfacial activity of copolymers and polymer functionalized nanoparticles in multiphase polymer systems holds deep scientific interest and enormous industrial importance. In addition to the variety of basic science questions they raise, these synthetic compatibilizers enable blends of immiscible polymers. Moreover, the core material of functionalized nanoparticles may offer additional chemical or physical functionality (magnetic, optical, thermal or electronic). However, even a basic understanding of how they work remains lacking. The research aims to measure, predict, and model the static and dynamic properties of nano-particle and co-polymer surfactants. Without such capability to make such measurements, and thus to develop a fundamental understanding of their operation, the rational design of synthetic compatibilizers for advanced polymer blends will remain impossible.Intellectual merit. The central intellectual merit of the proposed project is to develop and apply new techniques to measure and understand the static and dynamic properties of synthetic co-polymer and nanoparticle "surfactants" at polymer/polymer interfaces, essentially for the first time. This requires three specific aims be achieved:(1) To develop novel micro-scale techniques and tools. Two new and novel techniques will be developed: a micro-tensiometer, and an active microrheology technique to measure the surface viscoelasticity and nonlinear viscosity of the compatibilizer laden interface; (2) To use these new tools to measure and characterize the statics and dynamics of nanoparticle and copolymer surfactants. Specifically, surface pressure vs. concentration isotherms, surfactant diffusivity and interfacial viscoelasticity will be measured for nanoparticle and copolymer surfactants, whose properties are varied in a systematic and comprehensive manner; and (3) To develop theories that capture the measured behavior and make testable predictions; so as to generalize our results, provide an intuitive understanding of the mechanisms by which these synthetic compatibilizers work, and guide design rules. The proposed work is potentially highly transformative: not only does it propose to develop novel and unprecedented measurement capabilities, but also to develop fundamental and general understanding of the static and dynamic behavior of copolyer and nanoparticle surfactants, as well as intuition for how to design them.Broader impact. The broader impact of the proposed work is quite substantial. First, the measurement tools to be developed require only minute quantities of sample, yet would enable a control over interfacial composition and the measurement of interfacial tension and rheology, that would be unprecedented. This aspect of the proposed work would be truly transformative in terms of the information it would make accessible. The specific measurements would be the first of their kind, and would allow the first steps toward a fundamental understanding of the static and dynamic properties of nano particle surfactants at polymer/polymer interfaces. Such understanding would be potentially transformative as well, in that it that would enable the rational design and processing of advanced polymeric materials with desired properties. The groups will continue to be active in recruiting and mentoring under represented minority students and generally ambitious undergraduates in summer and academic year research projects, by leveraging the nationally recognized outreach infrastructure in UCSB's Materials Research Laboratory. A high school teacher will be involved in summer research, to impact his/her own experience as well as his/her students in future years. To reach out to the broader university community, a freshman seminar course will be developed for non-science students on the science and engineering of rheologically interesting products familiar from everyday life including foods and personal care products. The idea is to expose students to the interesting, ubiquitous and surprisingly understandable world of materials that are neither solid nor liquid. As part of this course, the investigators will post lecture notes and demonstration videos freely on the internet; following its successful development, we will write a descriptive article for Chemical Engineering Education, to encourage and facilitate related course content for other undergraduate or high school programs.