Studying the Processes of Assembly and Stimuli-Responsive Morphological Transformations in Solvated Macromolecular Nano-Assemblies

在化学部大分子、超分子和纳米化学项目的资助下，西北大学的Nathan Gianneschi和康涅狄格大学的Lucas R. Parent研究了两亲共聚物在纳米尺度上在水中的行为。两亲性共聚物是长链分子，具有亲水和亲油的性质。常见的两亲性化合物包括肥皂和洗涤剂。在这项工作中，电子显微镜用于观察两亲性共聚物在水中自组装过程中的分子尺度运动。实验研究检查了组装的途径和中间体。自组装控制有望应用于优化药物或化妆品运载工具，复合材料中的功能元件，光学传感器以及工业和生物中催化剂和试剂的运输。除了在实验室进行研究和指导外，该项目还与正在进行的学校外展工作相联系。活动包括为全国STEM高中学生和当地中学女生举办的探索工程和火花年度夏令营。此外，达芬奇计划旨在教育当地中学教师和管理人员加强课堂STEM教育。本研究采用原位液相透射电子显微镜技术研究了N，N-二甲基丙烯酰胺，N-异丙基丙烯酰胺和/或丙烯酸丁酯共聚物的大分子纳米结构的动态过程。特别强调的是发展对自组装/拆卸，动力学捕获，相变和形态转变的机制和途径的理解。聚合物的合成采用可逆加成-破碎转移聚合，可以控制分子量和多分散性。理解纳米尺度上的控制，有望将所研究的两亲共聚物应用于能够作为优化药物递送载体的组件，以及能够作为具有机械或流变响应的复合材料中的功能元件。此外，这种系统还具有运输催化剂和试剂的潜力。与该奖项相关的研究促进了对分散聚合物自组装离散结构的基本过程的理解，这不仅对纳米科学界，而且对一般的聚合物科学家都有重大意义。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With funding from the Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division, Nathan Gianneschi of Northwestern University and Lucas R. Parent of University of Connecticut examine how amphiphilic copolymers behave in water on the nanoscale. Amphiphilic copolymers are long chain molecules possessing both water-loving and oil-loving properties. Examples of common amphiphilic compounds include soaps and detergents. In this work, electron microscopy is used to observe molecular-scale movement during the self-assembly of amphiphilic copolymers in water. Experimental studies examine the pathways and intermediates for the assembly. Control of self-assembly has promise for applications such as optimized drug or cosmetic delivery vehicles, as functionalelements in composites, as optical sensors, and in the transport of catalysts and reagents in industry and biology. Beyond research and mentoring in a laboratory, this project connects with ongoing school outreach efforts. Activities include Exploring Engineering and Spark annual summer camps for national STEM high school students and local middle school girls. Also, the da Vinci Program is designed to educate local secondary school teachers and administrators on increasing classroom STEM education.This work employs in situ liquid phase transmission electron microscopy techniques to study the dynamic processes of macromolecular nanostructures involving copolymers of N,N-dimethylacrylamide, N-isopropylacrylamide and/or n-butyl acrylate. Particular emphasis is placed on developing an understanding of the mechanisms and pathways of self-assembly/disassembly, kinetic trapping, phase changes and morphological transformations. Polymer syntheses are conducted using reversible addition-fragmentation transfer polymerization which enables control over molecular weight and polydispersity. Understanding control at the nanoscale has promise for the application of investigated amphiphilic copolymers as components capable of performing as optimized drug delivery vehicles and as functional elements in composites capable of mechanical or rheological responses. Additionally, such systems also have the potential to transport catalysts and reagents. Research associated with this award advances understanding of the fundamental process of self-assembly of discrete architectures from disperse polymers which is of significant interest not only to nanoscience community, but to polymer scientists in general.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.