Specific Interactions In Polymer Systems

本研究涉及聚合物体系中特定相互作用的研究。这项工作的一部分旨在获得微观结构与氢键聚合物共混物中相同链接触分数或自集中之间相互作用的基本理解。测量这些混合物中氢键基团的比例也将用于确定氢键对流变性能的影响。这项工作将由拟议研究的第二部分补充，该部分涉及研究这些强相互作用系统中的能带的形状和宽度，以及它们如何受到相互作用和弛豫过程的影响。红外波段和拉曼谱线对局部环境和皮秒尺度动态非常敏感。通过将带形分析结果与应用超快二维红外光谱（2D-IR）技术获得的结果进行比较，将评估从聚合物光谱中获得有用信息的程度。控制高分子材料的混合和所谓的松弛现象（控制其机械和流变行为）的因素具有相当大的实际重要性。发现在分子水平上混合的聚合物（大多数都不能）可以产生具有新特性的材料。即使是相分离的聚合物也可以具有重要的性能，例如增强的抗冲击性，前提是相分离域的大小得到控制。这项研究将使用红外光谱来研究聚合物及其混合物中的特定相互作用和弛豫行为。这项工作还将通过让本科生和研究生参与实验室工作的机制来促进教育，从而教授他们光谱学和其他技术的基础知识。更独特的是，以前的NSF奖励支持的工作产生了基于CD的专著，完成了动画和互动程序，将扩展到产生将在网络上免费访问的讲座集。

TECHNICAL SUMMARYThis research involves studies of specific interactions in polymer systems. One part of the proposed work seeks to obtain a fundamental understanding of the interplay between microstructure and the fraction of same chain contacts, or self-concentration, in hydrogen bonded polymer blends. Measurements of the fraction of hydrogen-bonded groups in these mixtures will also be used to determine the effect of hydrogen bonding on rheological properties. This work will be complemented by the second part of the proposed research, which involves studies of the shapes and widths of bands in these strongly interacting systems and how these are affected by interactions and relaxation processes. Infrared bands and Raman lines are sensitive to local environment and picosecond scale dynamics. The extent to which useful information can be obtained from the spectra of polymers will be evaluated by comparing the results of band shape analysis to those obtained by applying ultrafast two-dimensional infrared spectroscopic (2D-IR) techniques. NON-TECHNICAL SUMMARYThe factors that govern both the mixing of polymer materials and so-called relaxation phenomena (which govern their mechanical and rheological behavior) is of considerable practical importance. Finding polymers that mix at the molecular level (most do not) can lead to materials with novel properties. Even polymers that phase-separate can have important properties, such as enhanced impact resistance, providing that the size of the phase separated domains are controlled. This research will use infrared spectroscopy to study both specific interactions and relaxation behavior in polymers and their mixtures. The work will also contribute to education through the mechanism of involving both undergraduate and graduate students in laboratory work, thus teaching them the fundamentals of spectroscopic and other techniques. More uniquely, work supported on previous NSF awards that resulted in CD based monographs, complete with animations and interactive programs, will be extended to produce sets of lectures that will be freely accessible over the web.