CAREER: Impact-Adaptive Conducting Polymers

下一代可穿戴或皮肤上的电子产品有可能通过提供非侵入性的、持续的生物识别监测来改变个性化的生物医学护理。可拉伸导电聚合物是一种特殊类型的塑料，可以导电并随身体运动而变形，已成为此类应用的主要材料。然而，这些聚合物由于其固有的机械性能，在以更快的速率变形时更容易断裂。 这对于直接应用于人体的电子设备是有害的，因为它们不断地经历动态运动。这个CAREER项目旨在开发一种新的自适应可拉伸导电聚合物，其韧性将随变形率而变化。具体来说，PI将探索和阐明实现和操纵这些自适应机械性能的基本化学设计原则。该项目的成功实施将使塑料电子产品具有更高的稳定性，可靠性和实用性，适用于下一代可穿戴或皮肤电子产品。这些特性还可以延长使用周期，从而减少塑料浪费，并有助于保护我们的环境。该项目的教育目标是提高加州中部地区的科学素养，这是一个历史上服务不足的地区，并创造一个更多元化的未来STEM劳动力。具体来说，PI将为当地K-12学生开发低成本的3D打印工具，以试验各种类型的聚合物，并了解聚合物在我们生活中的多样性，普遍性和重要作用。这些实验的修改版本将被整合到加州大学默塞德，西班牙裔服务机构的本科课程，让本科生接触新的软材料，并教育他们在聚合物科学的前沿。PI还计划在教育期刊上发表这些推广实验，希望传播这种低成本技术，以增加地球仪的科学素养和聚合物知识。技术概述使用导电聚合物实现实用的可穿戴和皮肤上电子器件的关键挑战是克服它们的粘弹性。这种应变率依赖性是非常有害的，因为使用这些聚合物制成的可穿戴和皮肤上的电子产品在涉及突然运动和冲击的条件下使用时，例如在运动期间，容易损坏。这个CAREER项目旨在开发一套化学设计原则，用于创建一种新的可拉伸导电聚合物，以对抗这种经典的，不利的应变率行为。这一目标将通过在分子链和纳米结构域水平上产生两种相互竞争的变形机制来实现。在该项目的第一阶段，PI将设计和合成一些具有有利于形成互穿胶束的化学结构的导电聚合物。不同的二次相互作用将被纳入胶束的表面和内部，作为功能手柄，用于调整两个竞争的变形机制。该项目的第二阶段将采用一整套化学、机械、电气和结构表征技术来研究这些聚合物。特别是，原位电阻/拉伸/小角度和广角X-射线散射将用于破译的结构-性能的关系和变形机制在表面和内部的胶束跨越各种长度尺度。该项目的第三阶段旨在通过在胶束表面创建有效的电荷传输路径来优化这些冲击适应性导电聚合物的电导率。通过该项目获得的聚合物设计原理和机械见解将为创建具有适应冲击程度的韧性的聚合物导体提供基础知识。该奖项反映了NSF的法定使命，并被认为是值得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的支持。

NON-TECHNICAL SUMMARY Next-generation wearable or on-skin electronics have the potential to transform personalized biomedical care by providing non-invasive, constant biometrics monitoring. Stretchable conducting polymers, a special type of plastic that conducts electricity and deforms with body movement, have become a main class of materials for such applications. However, these polymers break more easily when deformed at a faster rate because of their intrinsic mechanical properties. This is detrimental for electronics to be applied directly on human bodies since they are constantly undergoing dynamic movement. This CAREER project aims to develop a new class of adaptive stretchable conducting polymers with toughness that will scale with the rate of deformation. Specifically, the PI will explore and elucidate the fundamental chemical design principles for realizing and manipulating these adaptive mechanical properties. Successful execution of this project will lead to plastic electronics with enhanced stability, reliability, and practicality for next-generation wearable or on-skin electronics. These properties could also result in longer use cycles, and therefore reducing plastic waste and contributing to preservation of our environment. The educational objective of this project is to increase the scientific literacy in Central California, a historically underserved region, and create a more diversified future STEM workforce. Specifically, the PI will develop low-cost 3D printing tools for local K-12 students to experimenting with various classes of polymers and learn the diversity, pervasiveness, and important role that polymers play in our lives. Modified versions of these experiments will be integrated into the undergraduate curriculum at UC Merced, a Hispanic Serving Institution, to expose undergraduate students to new soft materials and educate them at the forefront of polymer science. The PI also plans to publish these outreach experiments in an education journal, with the hope of disseminating this low-cost technology to increase scientific literacy and knowledge of polymers across the globe.TECHNICAL SUMMARY A key challenge in realizing practical wearable and on-skin electronics using conducting polymers is to overcome their viscoelasticity. This strain rate-dependent property is highly detrimental as wearable and on-skin electronics made using these polymers would be prone to damage when used under conditions involving sudden movements and impact, such as during sports. This CAREER project aims to develop a set of chemical design principles for creating a new class of stretchable conducting polymers that defy this classic, unfavorable strain rate behavior. This objective will be realized by creating two competing deformation mechanisms at the molecular chain and nanoscopic domain levels. In phase I of the project, the PI will design and synthesize a number of conducting polymers with chemical structures that favor the formation of interpenetrated micelles. Different secondary interactions will be incorporated at the surface and interior of the micelles to serve as functional handles for tuning the two competing deformation mechanisms. Phase II of the project will employ a full suite of chemical, mechanical, electrical and structural characterization techniques to study these polymers. In particular, in-situ resistance/tensile/small- and wide-angle X-ray scattering will be used to decipher the structure-property relationships and deformation mechanisms at the surface and interior of the micelles across various length scales. Phase III of the project is aimed at optimizing the electrical conductivity of these impact-adaptive conducting polymers by creating effective charge transport pathways on the surface of the micelles. The polymer design principles and mechanistic insights gained through this project will lead to a body of fundamental knowledge for creating polymeric conductors that have toughness adaptive towards the degree of impact..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.