CAREER: Mechanics of Active Polymers and Morphing Structures: Determine the Role of Molecular Interactions and Stiffness Heterogeneity in Reversible Shape Morphing

该奖项全部或部分根据2021年美国救援计划法案（公法117-2）资助。该教师早期职业发展（CAREER）补助金将支持创新活性聚合物和变形结构力学的基础研究。在暴露于外部刺激时可以改变其形状并因此改变其功能的软变形聚合物对于许多应用是重要的，包括软机器人、人造肌肉和组织修复。尽管在这一令人兴奋和不断增长的领域取得了进展，但由于缺乏对液晶弹性体等新型活性聚合物的基本力学理解，创新变形材料和结构的合理设计、制造和应用受到了极大的限制。该研究项目将通过使用液晶弹性体作为模型材料系统，在新型活性材料的分子，材料和结构水平上建立缺失的复杂相关性。这项工作的教育目标是让不同层次的学生和公众参与变形材料和结构的前沿研究。将启动一个总体计划“Morphing Beyond Imagination”，向小学生提供简单而有趣的变形花，蜘蛛和章鱼演示，并将用于帮助高中生开发课程，以促进他们对STEM相关研究的追求。将通过暑期实习生和麦克奈尔奖学金计划向本科生，特别是女性和低收入家庭的学生提供研究经验。本项目的研究目标是以液晶弹性体为例，揭示分子间相互作用、非均匀材料性质和结构形状变形行为之间的复杂关系，并建立一个综合的实验和计算框架，为变形材料和结构的合理设计提供依据。为实现这一目标，该项目的具体任务包括：（1）建立分子间相互作用的相关性（交联密度、链排列和链长）和材料性质（双向形状变化中的刚度和致动应变），（2）建立一个集成的实验和计算框架来研究分子-材料相互作用下液晶弹性体结构的形状变形，以及（3）研究复杂空间介晶排列和刚度不均匀性下的形状变形和重新编程。这项工作的研究成果将有助于理解和优化新型活性聚合物和变形结构的设计与定制的链排列，刚度异质性，形状变形性能在复杂的负载条件和外部刺激。此外，该项目将对化学、物理、材料科学和生物医学工程等其他学科产生广泛影响。该奖项反映了NSF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评审标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).This Faculty Early Career Development (CAREER) grant will support research on fundamental studies of the mechanics of innovative active polymers and morphing structures. Soft morphing polymers that can change their shapes and therefore functionalities upon exposure to external stimuli are important for many applications, including soft robotics, artificial muscles, and tissue repair. Despite advancement in this exciting and ever-growing field, the rational design, manufacturing, and applications of innovative morphing materials and structures have been significantly limited by the lack of fundamental mechanics understanding of novel active polymers like liquid crystal elastomers. This research project will establish the missing complicated correlations across the molecular, material, and structural levels of novel active materials by using liquid crystal elastomers as a model material system. The educational objective of this work is to engage students at different levels and the general public to research frontiers in morphing materials and structures. An overarching program “Morphing Beyond Imagination” will be started, where simple and entertaining demonstrations of morphing flowers, spiders, and octopuses will be provided to elementary students and will be used to help develop curricula for high school students to promote their pursuit of STEM related studies. Research experiences to undergraduate students especially female and low-income students through a summer intern and a McNair scholar program will be provided. The research objective of this project is to uncover the complicated relationships among molecular interactions, heterogeneous material properties, and the shape morphing behavior of structures, and establish an integrated experimental and computational framework for the rational design of morphing materials and structures by using liquid crystal elastomers as an example. To achieve this objective, the specific tasks of this project include: (1) establish the correlations between molecular interactions (crosslinking density, chain alignment, and chain length) and material properties (stiffness and actuation strain in two-way shape changes), (2) build an integrated experimental and computational framework to study the shape morphing of liquid crystal elastomer structures under molecular-material interactions, and (3) investigate shape morphing and reprogramming under complicated spatial mesogen alignment and stiffness heterogeneities. The research outcomes of this work will help understand and optimize the design of novel active polymers and morphing structures with tailored chain alignment, stiffness heterogeneity, and shape morphing properties under complicated loading conditions and external stimuli. In addition, the project will generate broad impacts on a variety of other disciplines, including chemistry, physics, materials science, and biomedical engineering.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.