磁场对乙基纤维素胆甾型液晶相的影响

高分子胆甾型液晶相是一个在高分子和液晶领域都引起广泛兴趣的课题，不仅因为自然界中的多种生物大分子，如纤维素，多肽，DNA等可以形成胆甾型液晶相；而且由于胆甾相具有特殊的螺旋结构(如图1所示)，能产生一些特殊的光学性能，如强烈的旋光性，圆二色性和选择性反射光性能等；并带来相应的应用，正是由于高分子胆甾相材料的性能和应用，使得高分子胆甾相液晶的相态转变和结构变化也一直倍受关注。

EFFECTS OF MAGNETIC FIELD ON THE CHOLESTERIC PHASE OF ETHYLCELLULOSE

Liquid crystals are always composed of anisotropic constituents.In the presence of an electric or magnetic field,the arrangement of liquid crystalline molecules may be varied according to their different dielectric or diamagnetic anisotropy .The effect of a high magnetic field (9 4 T) on the cholesteric structure of et h yl cellulose (EC)/dicholroacetic acid (DCA) was investigated.The direction of ch olesteric helix axis aligned parallel to the direction of the magnetic field aft er the cholesteric solutions with fingerprint texture was treated in the magneti c field.It indicates that the diamagnetic anisotropy of the EC molecules is nega tive,which is caused by the conformation of the β-D-glucose backbone of t he cellulose molecule.