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

非技术概述：聚合物水凝胶是一种凝胶状材料，主要由水组成，通过液体中稀疏的长分子网状物结合在一起。水凝胶无处不在，可用于隐形眼镜等医疗材料、电池膜等能源材料、化工分离基质、尿布等日用品等。几十年来，人们一直知道这些材料在非常小的(纳米)尺度上是不均匀的。这个项目试图揭示这些不一致的本质，并探索它们与性能变化的关系。它将通过利用一些新型的超分辨率显微镜技术以及补充材料的结构-性能表征方法来做到这一点。教育部分利用研究计划作为激励下一代科学家和工程师的平台。其范围包括：(A)通过创建动手学习活动、视频和通过在线学习门户对K-12学生的指导，向STEM中代表性不足的群体进行外联；(B)扩大聚合物内容，并利用循证方法，如课堂上的初级文献和服务学习背景下的学生教学，开发创新课程；以及(C)通过本科生和研究生聚合物科学研究进行指导。其目的是绘制真实空间中凝胶的交联度的纳米级变化，并量化由此产生的非仿射变形。这些基本的形态研究将确立网络空间异质性对偏离经典弹性和旋转理论的预测的贡献。这项提议的及时性利用了最近光学超分辨率显微镜的非破坏性成像能力，以非破坏性地成像溶胀聚合物体系的纳米结构。这项拟议的工作将回答一个重要的科学问题--凝胶的纳米结构是什么--从而为许多行业提供潜在的影响。

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.