Polymer Adhesion at Extreme Rates and Temperatures

第一部分：聚合物胶粘剂是聚合物最普遍的应用之一，其在当今技术中的关键作用不断增长。从电子到医疗保健到建筑和施工，许多技术对聚合物粘合的依赖大大增加了这些界面遇到的环境和负载条件的范围。随着聚合物界面在防护装备和专门设计用于最大限度地减少人类暴露于潜在有害极端环境的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不断扩大。此外，由于聚合物粘合和粘合剂而产生的废物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，而且是粘合材料，这些材料通常难以分离，以便有效地回收或升级循环。该研究项目将导致在极端速率的负载和温度变化的聚合物界面的粘附力的新的理解。这一基础将有助于满足聚合物界面性质在极端条件下的基础知识的不足，我们预计，结果将指导新的协议的开发，用于分离界面，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，粘合，机械和热性能的表征方法，以及旨在应对技术前沿挑战的定制仪器的开发和实施。他们还将发展写作，管理，指导和演讲技巧。此外，研究小组将推出一个新的K-12外展计划，面向整个西部马萨诸塞州地区代表性不足的少数民族学生，以帮助激发未来的STEM职业生涯。第二部分：技术概述虽然聚合物界面强度已被经典地研究，但在材料结构如何控制高速机械和热加载的界面变形方面，悬而未决的问题和看似矛盾的结果仍未得到解决。PI的研究小组将结合联合收割机一种新的实验方法，称为功率放大动态力学分析（PADMA），与模型材料，以提供控制聚合物界面强度的见解和途径。三个模型聚合物系统的基础上，聚（丙烯酸正丁酯），这是广泛使用的许多目前的商业胶粘剂，将形成的基础上的研究。两个系统将被设计为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。此差异将与网络的交叉连接点相关联。这些材料将提供洞察力的弹性粘附长度尺度如何在高速发展，以及这种变化是如何与聚合物网络结构的变化。第三种材料系统，聚（丙烯酸正丁酯）-共-聚（二甲基丙烯酰胺）水凝胶与控制体积分数的水，将提供深入了解如何本地化的相变引发的高速率热变化改变界面分离。具体而言，水溶胀域的尺寸和互连性将与在高热速率下加载时界面强度的变化有关。总的来说，结果将有助于有限的，但不断增长的高速率聚合物性能的知识基础，特别是在接口。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.