Polymer Dynamics at Surfaces and in Complex Media

技术概述：这项研究将对聚合物如何在表面和受限几何中扩散产生新的理解。实验将基于新的荧光光谱实验平台，有时使用单分子分辨率（FCS，荧光相关光谱），有时使用FRAP（光漂白后荧光恢复）。当实现时，两个实验将产生空间分辨率为0.5 mm的空间分辨测量。许多有趣的和相关的变量将被执行，与现有的理论进行比较，并用于鼓励新理论的发展。提出了两项具体任务。首先，我们将确定从稀溶液中吸附到固体表面的聚合物的表面扩散如何取决于链长度和表面覆盖率。其次，我们将研究聚合物熔体在广泛的控制界面厚度范围内的扩散，从纳米到微米。这些实验将通过一种新的仪器平台来实现，该平台将荧光实验整合到表面力装置中。新颖的光学设计和特殊的尺寸稳定性将使我们能够测量横向表面扩散如何依赖于薄膜厚度。在固体表面方面，将探讨表面化学成分的关键作用。在界面的聚合物方面，我们将重点关注关键的控制方面，包括聚合物链长度依赖性，聚合物表面覆盖率，以及在分子薄膜的情况下，薄膜厚度，试图理解这个问题的普遍方面。非技术摘要：本研究侧重于聚合物材料物理性能的核心问题聚合物如何沿着固液界面和受限几何扩散。这些科学发现将对许多科学和技术应用产生新的理解，包括复合材料和纳米复合材料的粘附、相互扩散、摩擦和机械行为。这项工作将引入聚合物材料物理领域，具有单分子灵敏度的荧光方法在该领域具有特殊的前景。这将通过开发以前未在该学科中使用的新技术来改善聚合物领域的研究基础设施。研究生和本科生将与其他来自化学、化学工程、物理和材料科学的学生组成一个跨学科研究小组。

TECHNICAL SUMMARY: This research will develop new understanding of how polymers diffuse at surfaces and in confined geometries. The experiments will be based on using novel experimental platforms of fluorescence spectroscopy, sometimes with single-molecule resolution (FCS, fluorescence correlation spectroscopy), sometimes with FRAP (fluorescence recovery after photobleaching). As implemented, both experiments will yield spatially-resolved measurements with spatial resolution 0.5 mm. Many interesting and relevant variables will be performed, compared to available theory, and used to encourage the development of new theories. Two specific tasks are proposed. First, we will determine how surface diffusion depends on chain length and surface coverage for polymers adsorbed to solid surfaces from dilute solution. Second, we will study polymer melt diffusion over a wide range of controlled interfacial thickness, from nm to microns. These experiments will be enabled by a novel instrumental platform for integrating fluorescence experiments into a surface forces apparatus. Novel optical designs and exceptional dimensional stability will enable us to measure how lateral surface diffusion depends on thin film thickness. On the side of the solid surface, the critical role of the surface chemical composition will be explored. On the polymer side of the interface, we will focus on critical controlling aspects including the polymer chain length dependence, the polymer surface coverage, and in the case of molecularly-thin films, the film thickness, seeking to understand the universal aspects of this problem NON-TECHNICAL SUMMARY: This research focuses on a central problem of polymer materials physics performance how polymers diffuse along the solid-liquid interface and in confined geometries. The scientific findings will develop new understanding that is fundamental in many scientific and technical applications, including adhesion, interdiffusion, friction, and the mechanical behavior of composite and nanocomposite materials. This work will import, into the field of polymer materials physics, fluorescence methods with single-molecule sensitivity that hold exceptional promise for this field. This will improve research infrastructure in the polymer field by developing new techniques not previously used in this discipline. The graduate and undergraduate students will be part of an interdisciplinary research group with other students from chemistry, chemical engineering, physics, and materials science.