首页分析化学
   首页化学
   首页自然科学
0


液晶中的分离和相分离的核磁共振

NMR of Demixing and Phase Separation in Liquid Crystals
课程网址: http://videolectures.net/clc2010_zalar_dpsls/  
主讲教师: Boštjan Zalar
开课单位: 约瑟夫·斯特凡学院
开课时间: 2010-08-05
课程语种: 英语
中文简介:
分层是多组分液体和聚合物共混物中存在的众所周知的现象,通常由Flory Huggins自由能方法建模。在液晶中,它可以产生向列相和各向同性相的广泛共存范围[1]。由于许多不同的参数,相应温度浓度相图的确定通常是相当繁琐的任务:相的相对体积,向列相中各个介晶的向列顺序参数,以及相中的组分浓度。向列相和各向同性相。我们证明了氘核磁共振是一种特别有用的实验工具,用于研究nematics中的分子分离,提供同时测量所有上述参数,包括体积和受限系统,例如在液晶微乳液中,在掺杂的液晶单晶弹性体中和在光致异构化的nematics中。
课程简介: Demixing is a well-known phenomenon present in multi-component liquids and polymer blends, conventionally modeled by the Flory-Huggins free energy approach. In liquid crystals, it can result in a wide coexistence range of nematic and isotropic phases [1]. Determination of the respective temperature-concentration phase diagram is often a rather tedious task, due to many varying parameters: the relative volumes of the phases, the nematic order parameters of the individual mesogens in the nematic phase, as well as the concentrations of components in the nematic and isotropic phases. We demonstrate that deuteron NMR is a particularly useful experimental tool for the study of molecular segregation in nematics, providing for a simultaneous measurement of all the above parameters, both in bulk and confined systems, e.g. in liquid crystalline microemulsions, in doped liquid single-crystal elastomers, and in photoisomerizable nematics.
关 键 词: 分层; 浓度; 核磁共振
课程来源: 视频讲座网
最后编审: 2020-07-31:yumf
阅读次数: 78