乙基纤维素溶致液晶条带织构生长和松弛的动态过程

Dynamic Process of Growth and Relaxation of Banded Texture for Lyotropic Liquid Crystalline Ethyl Cellulose

用偏光显微镜和透射光强分析技术，观察乙基纤维秦－间甲酚和乙基纤维素－苯酚两个溶致液晶体系条带织构的生长和松弛的动态过程。条带具有固定的起始宽度，在生长过程中维持不变。ＴＯＡ曲线出现极大值峰将生长过程和松弛过程分成两个明显的阶段。松弛随浓度增高而变慢。生长随浓度增高而加快，但较低浓度时较慢的生长被较快的松弛所掩盖。条带的松弛还伴随着由微纤择优取向的向列织构转变为分子螺旋面排列的典型胆甾织构。此外，结果还表明条带织构生成的临界浓度高于液晶态形成的临界浓度，但低于两相并存向完全各向异性转变的浓度。

Light microscopy and transmission optical analysis(TOA)technique wereused to observe the dynamic process for growth and relaxation of banded texture in two lyotropicliquid crystalline systems:ethyl cellulose(EC)-m-cresol and EC-phenol solutions. Banded texturepresented a fixed original width and remained unchanged during growing. A maximum peakappearing on TOA curve evidently divided the process into two stages:growth and relaxation ofbands. Relaxation slowed down as concentration rose. Growth became fastor while concentrationincreased,but in the case of lower concentration,slower growth was concealed by fasterrelaxation. The relaxation of bands accompanied a nematic to cholesteric mesophase transition.Furthermore, experiments showed the banded texture can occur in solution with two phasecoexistence of isotropic and anisotropic phase. The critical concentration of formation of bandedtexture was between c_1( normally defined )and c_2(transition from two phase to whollyanisotropic).