GOALI: A Multiscale Approach on Interfacial and Structural Interlocking Between Polymer Grafted Shape Memory Pillars

技术摘要：该奖项基于互补的研究活动，包括杨在宾夕法尼亚大学(Penn)材料科学与工程(MSE)实验室的聚合物合成、制造和表征，以及Li在宾夕法尼亚大学/MSE的实验室与谢在通用汽车全球研究与开发中心(GM)的实验室合作在分子和亚结构(有序阵列)水平上的理论建模。它以他们在形状记忆聚合物(SMP)化学和表面化学方面的知识为基础，实现了坚固和工业规模的粘接。这一建议的重点是关于表面化学、地形和顺应性在不同长度尺度上的附着力的单独和联合作用的根本悬而未决的问题。具体地说，PI计划：(1)制作对尺寸、长宽比和间距进行精确控制的SMP柱阵列；(2)移植控制良好的聚合物刷子来操纵分子相互作用(例如氢键和离子-pi相互作用)，从而实现键合和脱粘；(3)系统地研究变形和恢复下互补的SMP柱上的黏附和剥离；以及(4)将实验结果与各个相关长度范围的多尺度模型进行比较，并开发出互锁干黏合的完整力学观点。非技术综述：聚合物之间的粘合在广泛的工业应用中发挥着重要作用。液态胶粘剂具有很强的粘附性，但其热固化耗能大，粘接一般不可逆。大自然为我们提供了可逆的干性粘连的显著例子，如牛至种子和壁虎足毛，粘性附着中不涉及液体或长时间的固化。这项提议寻求开发仿生超级胶状但可再加工的干燥粘合剂。它不仅将提供重要的科学见解，而且还将影响广泛的技术，包括电子包装、汽车和飞机组装以及软机器人。通过新的培训和外展机会，各级学生将接触到化学、材料科学和工程、软力学、纳米制造和计算建模等一系列不同的主题，包括通用汽车工业研究员的暑期讲座、将研究成果整合到课程中、通过暑期研究和高级设计项目让高中生和本科生参与进来，以及通用汽车全球研发中心的一名博士生进行工业实习。研究成果还将创造一个重要的机会，激发公众的兴趣，从而激发他们对科学、技术、工程和数学(STEM)的兴趣。

TECHNICAL SUMMARY:The award is based on complementary research activities, including polymer synthesis, fabrication and characterization in Yang's lab in Materials Science and Engineering (MSE) at the University of Pennsylvania (Penn), theoretical modeling at the molecular and meta-structural (ordered array) levels in Li's lab at Penn/MSE, in collaboration with Xie's lab at General Motors Global Research & Development Center (GM). It builds upon their knowledge in shape memory polymer (SMP) chemistry and surface chemistry toward robust and industrial scale adhesion. The focus of this proposal is on the fundamentally unresolved question concerning the individual and combined roles of surface chemistry, topography, and compliance on adhesion at different length scales. Specifically, the PIs plan to: (1) fabricate SMP pillar arrays with precise control over size, aspect ratio, and spacing; (2) graft well-controlled polymer brushes to manipulate molecular interactions (e.g. H-bonding and ion-pi interactions) for both bonding and debonding; (3) systematically study adhesion and peeling off on complementary SMP pillars under deformation and recovery, and (4) compare experimental results with multiscale modeling throughout each relevant lengthscale and develop a complete mechanistic view of interlocking dry adhesion. NON-TECHNICAL SUMMARY:Adhesion between polymers plays an important role in a wide range of industrial applications. Liquid based adhesives offer strong adhesion, however their thermal curing is energy intensive and the adhesion is generally not reversible. Nature provides us with remarkable examples of reversible dry adhesion as manifested in burdock seeds and gecko foot hairs, where no liquid or lengthy curing is involved in the adhesive attachment. This proposal seeks to develop biomimetic superglue-like, yet reworkable, dry adhesives. It will not only provide important scientific insights, but also impact a wide range of technologies, including electronic packaging, automotive and airplane assemblies, and soft robotics. Students at all levels will be exposed to a diverse range of topics in chemistry, materials science and engineering, soft mechanics, nanofabrication and computational modeling through new training and outreach opportunities, including summer lectures by the industrial researcher from General Motors, integration of the research outcome in courses, engagement of high school and undergraduate students through summer research and senior design projects, and industrial internship by a PhD student at General Motors Global R&D Center. The research outcome will also create a significant opportunity to excite the general public, thereby engaging their interest in Science, Technology, Engineering, and Mathematics (STEM).