Local Polymer Interfacial Mechanics: Effect of Topological and Chemical NanoPatterning

这笔赠款将回答有关聚合物在接近表面(几十到数百纳米范围内)的动态机械性能的公开问题，这些表面具有不同的几何限制和化学功能。表面附近的小尺度、局部聚合物行为显著影响薄膜中聚合物的力学行为、微电子中的纳米结构、药物输送装置和纳米复合材料，不仅在局部，而且在整体尺度上也是如此。从机械上理解和控制这些局部相界特性是设计和制造经济和技术上重要的产品和工艺的关键因素，从飞机结构复合材料部件到零排放车辆动力源。该项目将使用小规模实验方法与计算建模相结合，以加深对局部聚合物界面力学的理解，以促进最优材料设计。因此，该项目将为不同的博士后、研究生和本科生提供跨学科培训，通过参与当地的K-12科学活动来实现社区推广，并为数字数据管理和分发平台做出贡献。本研究的目标是通过将先进的原子力显微镜纳米压痕实验与目标有限元分析模拟相结合，应用于新型聚合物-基材界面模型系统，来表征受限聚合物中的局部机械梯度。由于聚合物在各种应用中的构型通常很复杂，将设计模型底物系统来研究由局部聚合物结构域与多个功能界面同时相互作用产生的多体化合物效应。我们将使用光刻技术制作一套包含拓扑和化学图案的聚合物-基板界面样品。将使用耦合的实验和模拟方法以高分辨率绘制局部弹性模量梯度图，以便数据分析将能够对复杂的实验伪影进行反卷积。先进的动态原子力显微镜模式也将被用来评估聚合物动力学的局部变化。模型系统被制造成在实际材料应用中对受限聚合物的明确定义的模拟，并通过利用组合方法提供了提高表征效率的途径。为了加速数据收集和分析，底物样品将被设计成可以在一个样品中探测到许多相间条件。总体而言，这些调查将为受限聚合物的性质和影响提供关键的基础性见解，并使使用聚合物和复合材料的多功能和坚固系统的合理设计成为可能。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。

This grant will answer open questions about the dynamic-mechanical properties of polymers in close proximity to surfaces (within tens to hundreds of nanometers) with varying geometric confinement and chemical functionalities. Small scale, local polymer behavior near surfaces dramatically affects the mechanical behavior of polymers in thin films, nanoscale structures in microelectronics, drug delivery devices, and nanocomposites, not only locally, but also at the bulk scale. Mechanistic understanding of, and control over, these local interphase properties is a crucial factor for the design and manufacture of economically and technologically important products and processes, from aircraft structural composite components to zero-emission vehicle power sources. This project will use small scale experimental methods in conjunction with computational modeling to develop a deep understanding of the local polymer interfacial mechanics to advance optimal material design. As such, the project will provide cross-disciplinary training to a diverse group of postdoctoral, graduate, and undergraduate trainees, enable community outreach by engaging with local K-12 science events, and contribute to digital data curation and distribution platforms.The goal of this research is to characterize the local mechanical gradients in confined polymers by applying advanced atomic force microscopy nanoindentation experiments coupled with targeted finite element analysis simulations to novel polymer-substrate interface model systems. Due to the generally complex configuration of polymers in various applications, model substrate systems will be designed to study multi-body compound effects arising from simultaneous interactions of local polymer domains with multiple functional interfaces. A suite of polymer-substrate interface samples containing topological and chemical patterns will be fabricated using lithography techniques. Local elastic modulus gradients will be mapped at high resolution using a coupled experimental and simulated approach such that data analysis will enable deconvolution of complex experimental artifacts. Advanced dynamic atomic force microscopy modes will also be employed to assess local changes in polymer dynamics. The model systems are fabricated as well-defined mimics of confined polymers in actual materials applications and provide an avenue for increased characterization efficiency by leveraging a combinatorial approach. To accelerate data collection and analysis, substrate samples will be designed such that many interphase conditions can be probed within one single sample. Overall, the investigations will provide key fundamental insights into the nature and impact of confined polymers and enable the rational design of multifunctional and robust systems using polymers and composites.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.