CAREER: Resolving and mapping of nanoscale heterogeneities in polymer gels and determination of their impact on properties.

非技术概要：聚合物水凝胶是一种果冻状的材料，主要由水组成，并由液体中的长分子稀疏网连接在一起。水凝胶无处不在，在隐形眼镜等医疗材料、电池膜等能源材料、化学工业的分离基质、尿布等商品中都有应用。几十年来，人们已经知道这些材料在非常小的（纳米）尺度上是不均匀的。该项目旨在揭示这些不一致性的本质，并探索它们与性能变化的关系。它将利用一些新型的超分辨率显微镜技术以及互补的材料结构-性能表征方法来实现这一目标。教育部分利用研究项目作为激励下一代科学家和工程师的平台。范围包括：(a)通过创建在线学习门户网站的实践学习活动、视频和对K-12学生的指导，向STEM中代表性不足的群体伸出援手；(b)扩大高分子材料的内容，并采用基于证据的方法开发创新课程，例如在课堂上使用原始文献，在服务学习的背景下进行学生教学；(c)指导本科生和研究生的高分子科学研究。技术概述：这项工作将整合研究、教学、外展和指导，阐明不受控制的纳米级非均质性对聚合物凝胶结构-性能关系的影响。目的是绘制真实空间中凝胶交联密度的纳米级变化，并量化随之而来的非仿射变形。这些基本形态学研究将确立网络空间异质性对偏离经典弹性和重复性理论预测的贡献。该建议的及时性利用了光学超分辨率显微镜对溶剂膨胀聚合物体系的纳米结构进行非破坏性成像的最新能力。这项提议的工作将回答一个重要的科学问题——凝胶的纳米级结构是什么——从而对许多行业产生潜在的影响。

Non-Technical Summary:Polymer hydrogels are jelly-like materials that consist primarily of water, and are held together by a sparse mesh of long molecules within the liquid. Hydrogels are ubiquitous, finding use in medical materials such as contact lenses, energy materials such as battery membranes, separation matrices for the chemical industry, commodities such as diapers, etc. These materials have been known for many decades to be non-uniform on a very small (nanometer) scale. This project seeks to reveal the nature of these non-uniformities and explore their relation to variations in performance. It will do so by utilizing a number of new types of super-resolution microscopy techniques together with complementary materials structure-property characterization approaches. The educational component leverages the research program as a platform to inspire the next generation of scientists and engineers. The scope includes: (a) outreach to underrepresented groups in STEM through creation of hands-on learning activities, videos and mentorship of K-12 students via an online learning portal; (b) expansion of polymer content and development of innovative curricula using evidence-based approaches such as primary literature in the classroom and student teaching in the context of service learning; and (c) mentoring through undergraduate and graduate polymer science research.Technical Summary:This work will integrate research, teaching, outreach and mentoring around elucidating the impact of uncontrolled nanoscale heterogeneities on the structure-property relationships of polymer gels. The objective is to map nanoscale variations in crosslink density of gels in real space and quantify the consequent non-affine deformation. These fundamental morphological studies will establish the contributions of network spatial heterogeneities to deviations from the predictions of classic theories of elasticity and reptation. The timeliness of the proposal draws on the recent ability of optical superresolution microscopies to non-destructively image the nanostructure of solvent-swollen polymer systems. The proposed work will answer an important scientific question -- what is the nanoscale structure of a gel -- and thus offer potential impact to a number of industries.