Collaborative Research: Deformation-Dependent Adhesion of Stretched Compliant Networked Polymer Systems

这笔赠款将集中于对改变柔软粘合材料的形状--例如，通过拉伸或压缩--如何改变其粘合性能的基本理解。现代的粘合理论最初是为了描述与橡胶等相对坚硬的材料的接触，但更柔软的粘性材料在生物、医学、工程和日常消费品中普遍存在。在过去的十年里，软固体表面力学已经成为一个令人兴奋的新研究领域，主要是因为一个令人惊讶的发现，即经典理论无法描述柔顺材料的接触行为，并且软材料与坚硬材料的粘附性非常不同。最近的实验、理论和模拟揭示了丰富的新物理，并为工程应用提供了一个强大的新设计空间。通过该研究项目开发的基础发现和材料将使新的应变控制、响应性粘合剂的开发成为可能，也将使学生研究人员参与到他们教育生涯的不同阶段，从本科生到博士后学者。每年夏天，该项目将建立一个“粘合工程夏令营”，以吸引威廉姆斯学院的学生参观普渡大学。顺应性聚合物的表面性质已被证明是以以前未曾预料到的方式随着整体变形而发生变化的。虽然最近关于软固体中应变相关表面应力的性质的争论推动了大量的实验和理论研究，但关注应变相关粘结的工作要少得多。通过使用集成的机械测试和直接成像进行测量，直接调查作为准静态和动态变形的功能的顺应性网络聚合物系统的正常粘接响应，该项目将建立对软材料的粘接如何在广泛的长度尺度、时间尺度和材料属性范围内通过变形来改变的基本理解。在这项合作拨款中，将通过实验、数值和理论工作来研究应变、粘着能、网络结构和材料松弛机制之间的相互作用。该项目的具体研究目标将是(I)量化拉伸、顺应性网络聚合物系统在整个长度尺度上的准静态附着力，以及(Ii)表征顺应性网络聚合物系统在动态变形期间的粘附性响应。该奖项反映了NSF的法定使命，并已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 grant will focus on developing a fundamental understanding of how changing the shape of soft, adhesive materials -- for example, through stretching or compression -- modifies their adhesive properties. Modern theories of adhesion were originally developed to describe contact with relatively stiff materials like rubber, but much softer sticky materials are ubiquitous in biology, medicine, engineering, and everyday consumer products. Over the past decade, soft solid surface mechanics has emerged as an exciting new field of study, driven largely by the surprising discovery that classic theories fail to describe the contact behavior of compliant materials and that soft materials adhere very differently than their stiffer counterparts. Recent experiments, theory, and simulations have revealed a rich array of new physics and suggest a powerful new design space for engineering applications. The fundamental discoveries and materials developed through this research project will enable the development of new strain-controlled, responsive adhesives and will also involve student researchers at various stages of their educational careers from undergraduates to postdoctoral scholars. An “Adhesion Engineering Summer Camp” will be established to bring Williams College students to visit Purdue University each summer of the project.The surface properties of compliant polymers have been shown to change as a function of bulk deformation in previously-unanticipated ways. While recent debates over the nature of strain-dependent surface stress in soft solids have motivated numerous experimental and theoretical studies, much less work has focused on strain-dependent adhesion. By performing measurements that directly investigate the normal adhesive response of compliant network polymer systems as a function of both quasi-static and dynamic deformation using integrated mechanical testing and direct imaging, this project will establish a fundamental understanding of how the adhesion of soft materials is modified by deformation across a broad range of length scales, time scales, and material properties. The interplay between strain, adhesion energy, network architecture, and material relaxation mechanisms will be investigated through the experimental, numerical, and theoretical work in this collaborative grant. The specific research objectives of the project will be to (i) quantify quasistatic adhesion to stretched, compliant network polymer systems across length scales and (ii) characterize the adhesive response of compliant networked polymer systems during dynamic deformation.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.