Structure of Highly Disordered Chains in Polymers by Vibrational Spectroscopy

通过振动光谱法研究聚合物中高度无序链的结构

• 批准号: 8701586
• 负责人: Robert Snyder
• 金额: $ 32.7万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-08-01 至 1991-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8701586&HistoricalAwards=false
• 关键词: Structure; Highly; Disordered; Chains; Polymers

This research is a study of conformation disorder in polymer systems by vibrational spectroscopy. Disorder plays an important role in determining the properties of polymeric materials, and this has stimulated much activity aimed at characterizing and understanding its complex nature. The range of applicability of vibrational spectroscopy to disorder has been seriously limited by the absence of a general, but practical, theory that can be used to provide quantitative relations between the conformational statistics and the infrared or Raman spectrum of a system of disordered chain molecules. Work by the authors has led to a model that enables general relations to be established between the structure and spectra of disordered chains. The model is based on the finding that the vibrations of disordered chains have some of the long-range coherence of ordered chains. Preliminary results on a simple system show that infrared band shapes calculated with this model reproduce the main features of those observed. This model will be modified to make it more widely applicable. A second approach to this problem will also be pursued in which the spectra of ensembles of disordered chains are generated numerically by summing the spectra computed for each constituent conformer. Spectra obtained in this way will be used to develop models that relate spectra and disorder, and to test conformational models that have been proposed for various polymers. In addition, vibrational spectroscopy and other available techniques, including inelastic neutron scattering, will be used to study a variety of disordered polymer systems. Special emphasis will be devoted to systems that exist in nonequilibrium states and to chain monolayers, liquid crystals, and liquid crystal polymers.

本研究是对高分子构象无序的研究 振动光谱学。 混乱在 在确定聚合物材料性能方面的作用，以及 这激发了许多旨在表征和 了解其复杂性。 的适用范围 振动光谱学对无序的研究受到严重限制 由于缺乏一个普遍的，但实际的，理论，可以 用于提供构象之间的定量关系 统计和红外或拉曼光谱的系统， 无序链状分子 作者的工作导致了一个模型，使一般 在结构和光谱之间建立关系 无序的链 该模型基于以下发现： 无序链的振动有一些长程的 有序链的相干性 一个简单的实验结果 系统显示了用该模型计算红外波段形状 再现所观察到的主要特征。 这个模型将被修改以使其更广泛 适用因 解决这个问题的第二种方法也将是 其中追求的光谱合奏无序链 通过对计算的光谱求和， 每一个组成构象。 以这种方式获得的光谱将 用于开发与光谱和无序相关的模型， 测试已提出的各种构象模型， 聚合物 此外，振动光谱和其他 可用的技术，包括非弹性中子散射， 将用于研究各种无序聚合物体系。 将特别强调现有的系统， 非平衡态和链单层，液晶， 和液晶聚合物。