Polymer Adhesion at Extreme Rates and Temperatures

第1部分：非技术性SUMMARY聚合物粘合剂是聚合物最普遍的应用之一，它们在当今技术中的关键作用只会越来越大。从电子到医疗再到建筑和建筑等众多技术对聚合物粘合的依赖，极大地增加了这些界面遇到的环境和加载条件的范围。随着聚合物界面有望在防护装备和机器人设备中发挥更重要的作用，这种环境和条件的范围将会扩大，这些设备专门设计用于将人类暴露在潜在有害极端环境中的程度降至最低。此外，由于聚合物粘合和粘合剂产生的废物数量正在以显著的速度增长。这些废物不仅是直接用于粘合的聚合物，还包括粘合材料，这些材料通常很难分离，以便有效地回收或升级循环。这项研究项目将导致对极端加载速度和温度变化下聚合物界面粘附性的新理解。这一基础将有助于弥补极端条件下聚合物界面性质基础知识的不足，我们预计这一结果将指导开发新的界面分离协议，帮助建立一个更可持续的社会。参与该项目的研究生和本科生将学习广泛的技能，包括聚合物合成和配方、粘附性、机械和热性能的表征方法，以及为应对技术前沿挑战而设计的定制仪器的开发和实施。他们还将发展写作、管理、指导和演示技能。此外，研究团队将推出一项新的K-12外联计划，面向马萨诸塞州西部地区代表性不足的少数族裔学生，以帮助激励未来在STEM的职业生涯。第2部分：技术总结虽然已经经典地研究了聚合物界面强度，但在材料结构如何控制高速率加载、机械和热加载的界面变形方面，悬而未决的问题和似乎相互矛盾的结果仍未解决。PI的团队将把一种名为功率放大动态力学分析(PADMA)的新实验方法与模型材料相结合，为控制聚合物界面强度提供洞察力和途径。以目前许多商用胶粘剂中广泛使用的聚丙烯酸丁酯为基础的三个模型聚合物体系将构成本研究的基础。两个系统将被设计成具有相似的低应变和低应变率特性，但不同的大应变和大应变率响应。这种差异将与网络的交叉链接连接相关联。这些材料将深入了解弹性粘合长度尺度如何在高速下演变，以及这种变化如何与聚合物网络结构的变化相关。第三种材料体系，聚丙烯酸丁酯-聚二甲基丙烯酰胺水凝胶，具有控制水的体积分数，将提供关于由高速热变化引发的局部相变如何改变界面分离的洞察。具体地说，水膨胀区域的大小和互连性将与在高热速加载时界面强度的变化有关。总体而言，这些结果将有助于高速率下有限但不断增长的聚合物性能知识库，特别是在界面上。这一知识将导致以更低的能量和不需要有害溶剂的方式分离聚合物界面的新方法。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。

PART 1: NON-TECHNICAL SUMMARYPolymer adhesives are one of the most pervasive applications of polymers, and their critical role in today’s technologies has only grown. The reliance of numerous technologies, from electronics to medical care to building and construction, on polymer adhesion has vastly increased the range of environments and loading conditions that these interfaces encounter. This range of environments and conditions will grow as polymer interfaces are expected to play more important roles in protective gear and in robotic devices that are specifically designed to minimize human exposure to potentially harmful extremes. Additionally, the quantity of waste that is created due to polymer adhesion and adhesives is growing at significant rates. This waste is not only polymers directly used in bonding but also the bonded materials, which are typically difficult to separate in order to be recycled or upcycled efficiently. This research project will lead to new understanding of adhesion at polymer interfaces at extreme rates of loading and temperature change. This foundation will help to meet a deficiency in the fundamental knowledge of polymer interfacial properties at extreme conditions, and we anticipate that the results will guide the development of new protocols for separating interfaces that help build a more sustainable society. Graduate and undergraduate students who participate in this project will learn a broad range of skills, including polymer synthesis and formulation, characterization methods for adhesion, mechanical and thermal properties, and the development and implementation of custom instrumentation designed to address challenges at the forefront of technology. They will also develop writing, management, mentoring, and presentation skills. Additionally, the team of researchers will launch a new K-12 outreach program geared toward under-represented minority students throughout the Western Massachusetts region to help inspire future careers in STEM. PART 2: TECHNICAL SUMMARYWhile polymer interfacial strength has been studied classically, open questions, and seemingly contradictory results, remain unresolved in how material structure controls the deformation of interfaces loaded, mechanically and thermally, at high rates. The PI's group will combine a new experimental method, called power amplified dynamic mechanical analysis (PADMA), with model materials to provide insight and pathways for controlling polymer interfacial strength. Three model polymer systems based on poly(n-butyl acrylate), which is broadly used in many current commercial adhesives, will form the foundation of the study. Two systems will be designed with similar low strain and low strain rate properties but different large strain and large strain rate responses. This difference will be associated with the network’s crosslink junctions. These materials will provide insight into how the elasto-adhesion length scale evolves at high velocities and how this change is related to changes in the polymer network structure. The third materials system, poly(n-butyl acrylate)-co-poly(dimethylacrylamide) hydrogels with controlled volume fractions of water, will provide insight into how localized phase transitions initiated by high rate thermal changes alter interfacial separation. Specifically, the size and interconnectivity of water swollen domains will be related to changes in interfacial strength when loaded at high thermal rates. Overall, the results will contribute to the limited, yet growing, knowledge base of polymer properties at high rates, especially at interfaces. This knowledge will lead to new methods for separating polymer interfaces with decreased energy and without the need for harmful solvents.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.