CAREER: Thermomechanical Property Control of Confined Conjugated Polymeric Thin Films

该项目由材料研究部的聚合物项目和促进竞争研究的既定计划（EPSCoR）共同资助。了解电子活性聚合物材料的动力学对于开发下一代可折叠和可变形电子器件至关重要。据设想，在不久的将来，植入式电子设备可以在人体和新兴电子产品之间提供独特的接口，从而恢复失去的人类功能，如听觉、视觉和身体运动。然而，目前还没有确定的设计角色来理解、控制和预测这种新型电子活性材料的柔软性和柔韧性。该项目旨在通过开发聚合物大分子动力学的基础新知识来解决这一挑战，从而为制造超软电子产品提供途径，使下一代软电子设备能够用于未来的可穿戴设备和植入物。南密西西比大学的研究人员将使用特殊仪器开发、测试和验证新的电子活性聚合物，并开发新的模型来预测和控制它们的柔软度。该研究将包括开发设计规则，通过测量、理解和操纵半导体聚合物的机械性能和分子纠缠行为，实现对半导体聚合物电子和机械性能的可调控制。除了研究生和本科生的研究参与外，该项目的教育工作将为当地K-12学生（包括大多数代表性不足的学生组成的学区）实施一个关于聚合物和光电材料的综合和好奇心驱动的虚拟和面对面教育平台。更广泛的影响还将包括美国南部的一个重点x射线/中子散射研讨会，为当地科学界带来新的科学技术。基于共轭聚合物的有机半导体具有独特的光电性能，已广泛应用于高效照明、医疗保健、能量收集和存储等领域。尽管它们的光电性能有了很大的进步，但预测和控制热机械性能的能力却落后了。因此，该项目的总体目标是开发新的设计规则，通过测量、理解和操纵其玻璃化转变温度以及分子纠缠行为来实现对共轭聚合物电子和机械性能的可调控制。南密西西比大学的研究人员将瞄准以下目标：1)准确确定共轭聚合物的玻璃化转变温度及其对器件相关薄膜限制态和体态机械性能的影响；2)阐明工程高缠结聚合物链的设计规律，了解缠结半刚性链对约束条件下独立薄膜最终断裂行为的影响；3)利用多模态原位光谱和散射技术了解半刚性共轭聚合物的变形机理，从而指导未来可变形电子器件的设计。通过该项目获得的基础知识将导致对共轭聚合物的热机械性能的精确控制，从而有助于未来软机器人、植入式医疗保健和强大的能量收集设备的发展。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。

This project is jointly funded by the Polymers Program in the Division of Materials Research and by the Established Program to Stimulate Competitive Research (EPSCoR).NON-TECHNICAL SUMMARYUnderstanding the dynamics of electronically active polymeric materials is crucial for the development of next-generation foldable and deformable electronic devices. It is also envisioned that in the near future implantable electronic devices could provide unique interfaces between the human body and emerging electronics, thus restoring lost human function, such as hearing, vision, and bodily movement. However, there are no established design roles to understand, control, and predict the softness and pliability of such new electronically active materials. This project aims to address this challenge by developing fundamental new knowledge on the dynamics of polymer macromolecules and thus provide a pathway to make ultra-soft electronics that can enable the next generation of soft electronic devices for future wearables and implants. The researchers at the University of Southern Mississippi will develop, test, and validate new electronically active polymers using special instrumentation and develop new models to predict and control their softness. The research will include development of design rules to achieve tunable control of the electronic and mechanical properties of semiconducting polymers by measuring, understanding, and manipulating their mechanical properties and molecular entanglement behavior.In addition to research involvement of graduate and undergraduate students, the educational effort of the project would implement an integrated and curiosity-driven virtual and in-person education platform on polymeric and optoelectronic materials to local K-12 students, including school districts comprising a majority of underrepresented students. Broader impacts will also include a focused Southern U.S. X-ray/neutron scattering workshop to bring new scientific techniques to the local scientific community.TECHNICAL SUMMARY Organic semiconductors based on conjugated polymers exhibit unique optoelectronic properties and have been widely applied in a broad range of applications for efficient lighting, health care, energy harvesting, and storage. Despite promising advances in their optoelectrical properties, the ability to predict and control thermomechanical properties is lagging behind. Thus, the overall goal of this project is to develop new design rules to achieve tunable control of the electronic and mechanical properties of conjugated polymers by measuring, understanding, and manipulating their glass transition temperature as well as their molecular entanglement behavior. Researchers at the University of Southern Mississippi will target the following goals: 1) accurately determine the glass transition temperature for conjugated polymers and its influence on the mechanical properties in both device-relevant thin-film confined states and bulk state; 2) illustrate the design rules for engineering highly entangled polymer chains to understand the role entangled semi-rigid chains have on final fracture behavior of free-standing thin films under confinement; and 3) understand the deformation mechanism of semi-rigid conjugated polymers using multimodal in-situ spectroscopy and scattering techniques, and thus guide the design of future deformable electronics. The fundamental knowledge gained through this project will lead to precise control of the thermomechanical properties of conjugated polymers, thus contributing to the development of future soft robotics, implantable health care, and robust energy harvesting devices..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.