Collaborative Research: Interfacial Self-healing of Nanocomposite Hydrogels

自修复聚合物是一种合成材料，能够在不需要人为干预的情况下自主修复损伤。它们在各种工程应用中显示出可持续技术的巨大潜力，包括人造肌肉和皮肤、柔性电子、软机器人和许多其他应用。然而，自修复聚合物的最新设计仍然处于试错阶段，缺乏足够的理论指导。该奖项支持基础研究，以阐明纳米复合水凝胶的自愈机制，由纳米颗粒交联的水介导的聚合物网络组成。从该项目中获得的知识将为能够在损坏后恢复其功能的自修复聚合物提供机械见解。这项研究不仅将促进自愈力学的基础科学，而且还将通过进一步开发和增强基于软材料的可持续技术来促进国民健康，繁荣和福利。该项目还将在固体力学、聚合物科学、机械工程和高性能计算领域培养不同的学生，以促进下一代劳动力的发展。该项目的教育目标将通过课程开发，本科生研究机会，高中生暑期研究计划，K-12教师计划的研究经验和K-12外展计划来实现。将作出特别努力，让代表性不足的学生参与这一项目。尽管在自修复聚合物的合成和应用方面进行了广泛的研究，但构建自修复性能与材料/修复设置之间的机械关系仍然具有挑战性。关键的技术障碍是如何物理模拟聚合物网络在自修复过程中的微观结构演变。该项目的中心假设是，纳米复合材料水凝胶的自愈合强度由聚合物链在断裂界面上的扩散和随后与纳米颗粒形成的交联决定。为了验证这一假设，该项目结合分子动力学模拟和分析理论，研究聚合物链在自愈合过程中的微观扩散-反应行为和自愈合后的宏观界面强度。计算和理论预测将系统地验证与纳米复合材料水凝胶的实验研究组成的几种材料组合物，如颗粒浓度，粒度和水的分数，并在各种外部愈合控制，如温度和延迟时间。跨学科的努力将开辟有前途的途径，定量了解多尺度力学的自我修复聚合物，并提供基本的设计原则，高性能的自我修复polymer.This奖项反映了NSF的法定使命，并已被认为是值得的支持，通过评估使用基金会的智力价值和更广泛的影响审查标准。

Self-healing polymers are synthetic materials capable of autonomously repairing damages without human intervention. They have shown great potentials for sustainable technologies in diverse engineering applications, including artificial muscles and skins, flexible electronics, soft robotics and many others. Nevertheless, the state-of-the-art design of self-healing polymers remains at the trial-and-error stage with insufficient theoretical guidance. This award supports fundamental research to elucidate the self-healing mechanics of nanocomposite hydrogels that consist of water-mediated polymer networks crosslinked by nanoparticles. The knowledge obtained from this project will provide mechanistic insights into self-healing polymers that are able to restore their functionality after damage. The research will not only promote the fundamental science of self-healing mechanics, but also advance the national health, prosperity, and welfare through further development and enhancement of soft-materials based sustainable technologies. This project will also train a diverse group of students in the areas of solid mechanics, polymer science, mechanical engineering, and high-performance computing for next-generation workforce development. The educational objectives of the project will be realized through curriculum development, undergraduate research opportunities, summer research program for high school students, research experience for K-12 teachers program, and K-12 outreach program. Special efforts will be made to involve underrepresented students in this project. Despite extensive studies in the syntheses and applications of self-healing polymers, constructing the mechanistic relationship between self-healing properties and material/healing settings remains challenging. The key technical barrier is how to physically model the microstructure evolution of the polymer networks during the self-healing process. The central hypothesis of this project is that the self-healing strength of nanocomposite hydrogel is governed by the diffusion of polymer chains across the fractured interface and subsequent crosslinks formed with nanoparticles. To test this hypothesis, the project integrates molecular dynamics simulations and analytical theories to study microscopic diffusion-reaction behaviors of polymer chains during self-healing process and macroscopic interfacial strengths after self-healing. The computational and theoretical predictions will be systematically validated with experimental studies of nanocomposite hydrogels composed of several material compositions, such as particle concentration, particle size, and water fraction, and under various external healing controls, such as temperature and delaying time. The interdisciplinary effort will open promising avenues for quantitatively understanding the multiscale mechanics of self-healing polymers and providing fundamental design principles of high-performance self-healing polymers.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.