氰乙基纤维素/二甲基乙酰胺液晶溶液的研究

STUDIES ON LYOTROPIC LIQUID CRYSTALLINE SOLUTIONS OF CYANOETHYL CELLULOSE/DIMETHYL ACETAMIDE

本文利用Abbe折射仪,热台偏光显微镜,小角光散射等方法研究了氰乙基纤维素/二甲基乙酰胺液晶溶液的形成,形态结构和某些性质。溶液随浓度的增加,从各向同性态经过两相共存状态,转变成为单一的液晶态。该液晶是胆甾型的。溶液的双折射Δn随浓度的增加或温度的降低而增大。在无外力作用时,液晶相由许多无规分布的取向微区组成。液晶溶液受切应力后形成“条纹结构”,大分子链沿切应力方向取向,并在各条纹中排列有序。

The formation, texture and some properties of cyanoethyl cellulose (CEC)/dimethyl aceta-mide (DMA) mesomorphic solutions were studied. The solutions could transform from isotro-pic to anisotropic states through a biphasic range as increasing the concentration. The liquid crystal was cholesteric. Birefringence of the solutions increased with increasing the concentration or dropping of the temperature. The mesomorphic aggregates were composed of many domains whose orientation directions were different when the solutions were in nature. The liquid crystalline solutions which had been sheared could form 'band-like' structure in which molecular chains oriented nearly along the lines of the shear. The orientation directions of the molecular chains were different slightly between the neighboring bands.