Understanding and Exploiting the Transport Behavior of Polymers in Confined Geometries

目前有显着的知识差距，从根本上理解的热力学和传输性能的聚合物在有限的几何形状（如超薄膜），以及这些性能的依赖膜厚度和制备条件。 最近的研究表明，当膜厚度降低到某一临界厚度以下时，各种聚合物膜的性质偏离本体行为。 我们最近的测量表明，通过聚合物超薄膜的本体扩散的质子传导性的聚合物薄膜的质子传导性并没有出现以类似的方式降低，而膜厚度的降低显着减少。 这项工作的首要目标是表征质子传输和扩散行为的聚合物在受限的几何形状，阐明这种行为的长度尺度和幅度，并制定一个自我一致的和全面的基本理解的机制，负责观察到的现象。 该提案的智力价值可以广泛地定义为：（1）表征聚合物超薄膜中的质子传输，（2）开发基本模型来解释聚合物超薄膜的物理化学性质，以及（3）利用观察到的行为，使用现有材料和工艺来提高燃料电池质子交换膜的性能。 这项活动的广泛影响包括：（1）提供克服微光刻中的一些障碍的指导和机会，以使微电子工业受益，（2）提供增强用于燃料电池的聚合物膜性能的方法，（3）以协同地混合建模和实验的方式教育本科生和研究生，（4）加强少数民族学生教育，改善中学科学教育。

Currently there are significant knowledge gaps in fundamentally understanding the thermodynamic and transport properties of polymers in confined geometries (e.g. ultra-thin films), and the dependence of these properties on film thickness and preparation conditions. Recent studies have shown that a wide variety of polymer film properties deviate from bulk behavior as the film thickness decreases below some critical thickness. Our recent measurements suggest that bulk diffusion of penetrants through polymer ultra-thin films decreases dramatically with decreasing film thickness while the proton conductivity of polymer films does not appear to decrease in a similar manner. The overarching goals of this work are to characterize the proton transport and diffusion behavior of polymers in confined geometries, elucidate the length scales and magnitudes of such behavior, and develop a self consistent and comprehensive fundamental understanding of the mechanisms that are responsible for the observed phenomena. The intellectual merits of the proposal can broadly be defined as: (1) characterizing the proton transport in polymer ultra-thin films, (2) developing a fundamental model to explain the physiochemical properties of polymer ultra-thin films, and (3) exploiting the observed behavior to produce enhanced capabilities for proton exchange membranes for fuel cells using existing materials and processes. The broader impacts of this activity include: (1) providing guidance on and opportunities for overcoming some of the roadblocks in microlithography to benefit the microelectronics industry, (2) providing a way to enhance polymer membrane performance for fuel cells, (3) educating undergraduate and graduate students in a manner that synergistically blends modeling and experiment, and (4) enhancing underrepresented and minority student education and improving secondary school science education.