Performance of Pressure Sensitive Adhesives on Soft and Slippery Materials

压敏胶粘剂是一类在施加轻微的外部压力后粘合在基材上的材料。它们在日常生活中被广泛用于粘接干燥和坚硬的表面。这些材料尚未扩展到其他重要的应用领域，从医疗保健到建筑，其中表面柔软，潮湿和光滑，如皮肤，组织或伤口。这些材料通常很软，在压力下会变形。这些软质材料的机械性能，而不仅仅是它们的表面，会影响附着在表面的能力。这项研究将确定基材性能与粘合剂性能和失效之间的基本关系。更好地了解粘合剂在柔软和潮湿表面上的性能和失效机制，可能会对健康或柔性可穿戴电子等行业产生重要影响，在这些行业中，新的创新粘合剂可以开辟新的技术应用。这项工作还将使高中生和本科生深入接触研究和材料。压敏胶粘剂的粘弹性使得理解其机械响应具有挑战性，特别是在大应变极限下。该项目旨在通过测试两个科学假设，为柔顺和潮湿表面上的压敏粘合剂的性能提供所需的知识。首先，增加基材的柔度会增加裂纹尖端的耗散区大小，并影响胶粘剂的性能和失效模式。其次，对于湿表面上的粘附，表面能比体积耗散的重要性应该增加。为了验证这些假设，将获得对分层系统中胶粘剂内应力集中以及暴露于水时其表面能变化的更好的基本理解。本研究系统的实验方法分为三个目的。(1)开发一个先进的工具包来研究压敏胶在柔软、潮湿和光滑表面上的性能；(2)了解压敏胶在柔软和潮湿表面上的剥离粘附；(3)表征柔软和潮湿基材上的粘性。外展和教育部分包括与当地高中的合作，让学生参与研究经验，重点关注代表性不足的学生。

Pressure sensitive adhesives are a class of materials that bind to a substrate after a light external pressure has been applied. They are used extensively in daily life for adhesion to dry and rigid surfaces. These materials have not been extended to other important application areas ranging from healthcare to construction where the surfaces are soft, wet, and slippery, such as skin, tissue, or wounds. These materials are often soft and can deform under pressure. The mechanical properties of these soft materials, not just their surface, can affect the ability to adhere to that surface. This research will determine the fundamental relationships between the properties of a substrate and the performance and failure of adhesives. A better understanding of performance and failure mechanisms for adhesives on soft and wet surfaces could have important impact in industries as diverse as health or flexible wearable electronics where new innovative adhesives could open new technological applications. This work will also engage high school and undergraduates in an intensive exposure to research and materials.The viscoelastic nature of pressure sensitive adhesives makes understanding their mechanical response challenging, especially in the limit of large strains. The project aims to provide the needed knowledge for the performance of pressure sensitive adhesives on compliant and wet surfaces by testing two scientific hypotheses. First, increasing the substrate compliance should increase the size of the dissipation zone at a crack tip, and affect the performance & mode of failure of adhesives. Second, the importance of surface energy over bulk dissipation should increase for adhesion on wet surfaces. To test these hypothesis a better fundamental understanding of stress concentration within an adhesive in stratified systems as well as of the change in their surface energy upon exposure to water will be acquired. This research systematic experimental approach is divided into three aims. (1) Develop an advanced toolkit to study the performance of pressure sensitive adhesives on soft, wet, and slippery surfaces, (2) Understand peeling adhesion of pressure sensitive adhesives from soft and wet surfaces, and (3) Characterize tack on soft and wet substrates. The outreach and educational components include a partnership with local high schools to engage students in the research experience with a focus on underrepresented students.