CAREER: Building Hierarchical Polymers with Light to Unify Softness, Resilience, and Conductivity

非技术总结：聚合物由于其固有的低成本和可调特性在我们的日常生活中无处不在。它们的多功能性是其化学成分和分子连接方式的直接结果。然而，与自然系统相比，目前对组成和结构的控制相形见绌，自然系统具有为特定功能调整的进化层次结构。因此，合成材料与生物材料的结合往往很差，例如，妨碍了研究和治疗疾病的能力。该计划的目标是制备柔软和有弹性（即，强而有弹性）的聚合物，模拟自然组织（例如，皮肤，心脏和肺），同时额外赋予电导率，以促进现代电子设备和生物系统之间的通信。改善设备和生物学之间的交流将使科学家和医生能够更好地研究和控制一个新兴研究领域的自然功能：生物电子学。提出的材料建立在工业相关聚合物的基础上，通过引入新的分子结构来增加柔软度，以便在不影响强度的情况下更好地与自然系统界面。此外，将利用低能量可见光来确定化学反应发生的时间和地点，从而使分层结构的制造过程能够适应未来在3D打印中的实施。最终，要解决这些具有挑战性的跨学科科学问题，需要一支准备充分的多样化科学队伍，而STEM的多样化需要在专业发展的早期阶段进行教育和参与。因此，作为该项目的一部分，将在德克萨斯大学奥斯汀分校开设一门大一本科聚合物研究课程，同时为东奥斯汀当地的初中/高中学生提供一个实践聚合物活动，那里有大量未被充分代表的群体。总的来说，拟议的研究通过基础发现促进科学进步，教育下一代STEM劳动力，促进改善健康和福利的先进材料的开发，符合国家利益。技术概述：描述了产生具有组织样柔软性和弹性（强度+弹性）的分层导电聚合物的互补策略。虽然合成聚合物在我们的日常生活中无处不在，但与自然界中的聚合物相比，对其组成、结构和形态的控制显得微不足道，这限制了它们的功能和可能的最终用途。柔软度和弹性是许多生物材料（如皮肤、心脏和肺组织）表达的两个力学参数，以防止破裂，但将它们综合起来仍然是难以捉摸的。此外，通过现代技术进行的通信依赖于电子传输，而生物系统则通过离子的运动来运作。这些机械和通信差异阻碍了通过医学生物电子学研究和控制生物过程。为了缩小技术-生物学的差距，提出了一种自下而上的方法，使用快速时空控制的基于光的聚合化学来获取具有复杂结构和可定制机械和传输特性的材料。这些材料分为两类：1)ABA三嵌段共聚物和2)互穿聚合物网络（ipn）。在这些材料中，跨越长度尺度的多层分层结构将提供统一柔软性、回弹性和导电性的缺失环节，揭示关键但基本的结构-性能关系，为进一步的材料优化提供信息。鉴于嵌段共聚物和ipn的普遍性，以及对生物电子学的电子/离子转导和3D打印的光基化学的新兴兴趣，拟议研究的科学发现将为无数下一代应用（例如，生物电子学和软机器人）的出现奠定基础。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。

NON-TECHNICAL SUMMARY:Polymers have become ubiquitous in our daily lives owing to their inherent low cost and tunable properties. Their versatility is a direct result of their chemical composition and the way in which the molecules are connected. However, current control over both composition and structure pales in comparison to that found in natural systems, which have an evolved hierarchical architecture tuned for specific functions. As such, synthetic materials often interface poorly with biological ones, precluding, for example, the ability to study and treat disease. This program targets the preparation of soft and resilient (i.e., strong and stretchy) polymers that mimic natural tissue (e.g., skin, heart, and lung), while additionally imparting electrical conductivity to facilitate communication between modern electronic devices and biological systems. Improving the communication between devices and biology will allow scientists and doctors to better study and control natural functions in an emergent area of research: bioelectronics. The proposed materials build off a foundation of industrially relevant polymers by introducing new molecular architectures to increase softness for better interfacing with natural systems without compromising strength. Moreover, low-energy visible light will be leveraged to define when and where chemical reactions take place, enabling the fabrication of hierarchical structures in a process that is amenable to future implementation in 3D printing.Ultimately, to solve these challenging interdisciplinary scientific problems requires a well-prepared diverse scientific workforce, and diversification in STEM requires education and engagement at an early stage of professional development. Therefore, as part of this project a first-year undergraduate polymer research course will be developed at the University of Texas at Austin, along with a hands-on polymer activity for students at local middle/high schools in East Austin with large populations of underrepresented groups. Overall, the proposed research serves the national interest by promoting the progress of science through fundamental discovery, educating the next generation STEM workforce, and facilitating the development of advanced materials that will improve health and welfare.TECHNICAL SUMMARY:Complementary strategies to generating hierarchical conductive polymers with tissue-like softness and resilience (strength + elasticity) are described. While synthetic polymers have become ubiquitous in our daily lives, control over their composition, structure, and morphology pales in comparison to that found in nature, limiting functionality and possible end-use applications. Softness and resilience are two mechanical parameters expressed by a number of biological materials (e.g., skin, heart, and lung tissue) to prevent rupture, yet harnessing these together synthetically remains elusive. Moreover, communication through modern technology relies on electronic transport, while biological systems operate via the movement of ions. These mechanical and communication discrepancies have hampered the study and control of biological processes via bioelectronics for medicine. To close the technology-biology gap, a bottom-up approach using rapid spatiotemporally controlled light-based polymerization chemistry to access materials with complex architectures and tailorable mechanical and transport properties are proposed. The materials sit in one of two categories: 1) ABA triblock copolymers and 2) interpenetrating polymer networks (IPNs). Multiple levels of hierarchical structure across length scales within these materials will provide the missing links to unify softness, resilience, and conductivity, unveiling critical, yet fundamental, structure-property relationships to inform further materials optimization. Given the generality of block copolymers and IPNs, and emerging interest in electronic/ionic transduction for bioelectronics and light-based chemistry for 3D printing, the scientific discoveries from the proposed research will lay a foundation from which a myriad of next-generation applications will emerge (e.g., bioelectronics and soft robotics)..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.