Proton Multiple Quantum NMR Studies of Space and End Chain Conformation in Liquid Crystals

液晶空间和端链构象的质子多量子核磁共振研究

• 批准号: 8700081
• 负责人: Gary Drobny
• 金额: $ 24万
• 依托单位: University of Washington
• 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: 1987-06-01 至 1990-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8700081&HistoricalAwards=false
• 关键词: Proton; Multiple; Quantum; NMR; Studies

The problem of the conformation and ordering of flexible chains in anisotropic phases has attracted a good deal of attention in recent years. The motivation of most of this work is a desire to understand the manner in which alkyl chains pendant to aromatic cores influence mesomorphic phase properties and stability. Liquid crystal polymers have also been the subject of research as possible sources of high tensile strength fibers and coatings, and for their possible applications in electro-optic devices. Although polymers with rigid backbones do not generally form liquid crystalline phases, or decompose before melting into memorphic phases, the introduction of flexible spacer chains into the polymer backbone will lower mesophase transition temperatures to below the range of thermal decomposition. Deuterium NMR spectroscopy has been the principal tool for probing the microscopic structure and dynamics of end and spacer chains, and for testing models of chain ordering in nematic phases. Professor Drobny proposes an approach to studying spacer and end chain ordering in the nematic phase and in several in low temperature mesophases using multiple quantum spectroscopy. Rather than test models of chain ordering and conformation, conformational probabilities and order tensor elements will be directly calculated from proton-proton and proton-carbon dipolar couplings obtained from multiple quantum spectra.

柔性链的构象和有序化问题 在各向异性相中， 近年 这项工作的动机是希望 理解烷基链悬挂在芳族化合物上的方式， 核心影响介晶相的性质和稳定性。 液晶聚合物也是研究的主题， 高拉伸强度纤维和涂层的可能来源， 以及它们在电光器件中的可能应用。 虽然具有刚性主链的聚合物通常不形成 液晶相，或在熔化成 记忆阶段，引入灵活的间隔链， 聚合物主链将降低中间相转变温度 低于热分解的范围。 氘核磁共振 光谱学一直是探测 末端和间隔链的微观结构和动力学，以及 用于测试在可重构阶段中的链式排序模型。 Drobny教授提出了一种研究间隔子和末端的方法， 链序在双相和几个在低 温度中间相使用多量子光谱。 而不是测试模型的链排序和构象， 构象概率和顺序张量元素将是 由质子-质子和质子-碳偶极直接计算 从多个量子光谱获得的耦合。