CAREER: Spatiotemporal Behavior of Stimuli- Responsive Soft Materials in Non-Equilibrium Processes

这项学院早期职业发展(Career)基金将研究刺激响应型软材料(SSM)的非平衡动力学过程。SSM可以改变其结构、形状或功能，以响应外界刺激，如热、化学物质、光辐射、电场或磁场。在外界刺激的作用下，SSM通过扩散、反应、粘弹性松弛等非平衡动力学过程从一种平衡态演化到一种新的平衡态。这些动力学过程不仅决定了SSM的响应速度，而且决定了其结构、形状和功能的时空演化方式。了解响应动力学是设计可编程SSMS和开发新兴技术的关键一步，例如4D打印、自动折叠折纸和自动推进机器人。通过解开耦合的动力学过程，以及动力学与惯性和重力的相互作用，这一赠款将实现SSMS的可编程重构、振荡和运动。这笔赠款在教育和技术方面产生了更广泛的影响。它将通过教学、研究和咨询为不同的本科生和研究生群体提供培训机会。研究工作将纳入研究生班，发展为K-12外联活动的示范，并在会议上广泛传播。这笔赠款的长期成果是具有程序化和动态刺激响应的SSMS，这将对软机器人、生物医学设备、能量收集和可重构结构产生影响。本赠款的目标是解开SSMS中耦合的非平衡动力学过程，以及动力学与惯性和重力的相互作用，以控制它们的时空响应。具体地说，赠款将(1)解开耦合的非平衡过程以实现可编程重新配置，(2)利用动力学和惯性的耦合来实现自主振荡，以及(3)利用动力学和重力之间的相互作用来实现受控运动。三种SSM模型体系，包括光热响应型形状记忆聚合物、光热响应型水凝胶和湿度响应型聚合物，将用非线性非平衡场理论进行分析建模、计算模拟、实验制备和表征。这项奖励的成功将推进多物理本构模型领域对SSMS时空行为的预测，并为SSMS实现可编程时空重构和快速动态运动提供设计指南。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This Faculty Early Career Development (CAREER) grant will investigate the non-equilibrium kinetic processes of stimuli-responsive soft materials (SSMs). SSMs can change their structures, shapes or functions in response to external stimuli, such as heat, chemicals, light radiation, electrical fields, or magnetic fields. Triggered by an external stimulus, a SSM evolves from one equilibrium state to a new one through non-equilibrium kinetic processes, including diffusion, reaction, viscoelastic relaxation, etc. The kinetic processes not only determine the response speeds of SSMs, but also govern how they spatiotemporally evolve their structures, shapes and functions. Understanding the response kinetics is a key step to designing programmable SSMs, and developing emerging techniques, such as 4D printing, self-folding origami, and self-propelled robots. By unraveling the coupled kinetic processes, and the interplay of kinetics with inertia and gravity, this grant will achieve programmable reconfiguration, oscillation and locomotion of SSMs. This grant has broader impacts in education and technology. It will provide training opportunities to a diverse group of undergraduate and graduate students through teaching, researching and advising. The research work will be included into graduate classes, developed into demonstrations for K-12 outreach activities, and widely disseminated in conferences. The long-term deliverables of this grant are SSMs with programmed and dynamic stimuli-responses, which will have impacts on soft robotics, biomedical devices, energy harvesting, and reconfigurable structures.The objective of this grant is unraveling coupled non-equilibrium kinetic processes and the interplay of kinetics with inertia and gravity in SSMs to control their spatiotemporal responses. Specifically, the grant will (1) unravel coupled non-equilibrium processes to achieve programmable reconfiguration, (2) utilize coupling of kinetics and inertia to enable autonomous oscillation, and (3) harness interplay between kinetics and gravity to attain controlled locomotion. Three model SSM systems, including photo-thermally responsive shape memory polymers, photo-thermally responsive hydrogels, and humidity-responsive polymers, will be analytically modeled by a nonlinear non-equilibrium field theory, computationally simulated, and experimentally fabricated and characterized. The success of the grant will advance the field of multiphysics constitutive modeling on predicting spatiotemporal behavior of SSMs, and provide design guidelines for SSMs to achieve programmable spatiotemporal reconfiguration, and fast and dynamic motion.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.