光聚合对乙基氰乙基纤维素/丙烯酸胆甾相结构的影响

The Effect of Photopolymerization on the Cholesteric Structure of Ethyl-Cyanoethyl Cellulose/Acrylic Acid Liquid Crystalline Solution

乙基氰乙基纤维素 [(E -CE)C]能够很好地溶解在丙烯酸 (AA)中并形成胆甾型液晶溶液。在 (E -CE)C/AA溶液中加入适当的光引发剂 ,采用紫外光引发聚合抑制聚合过程中相分离的发生 ,可以制得保持胆甾相结构的复合物。聚合反应会对胆甾相的结构产生一定的影响。文章研究了溶液浓度、聚合温度和 (E -CE)C分子量等因素对聚合以后胆甾相选择反射光波长及结构的影响。

The (E-CE)C/PAA composite with cholesteric structure and without phase separation can be prepared by photopolymerizing the AA in (E-CE)C/AA solution. The cholesteric structure is somewhat changed after polymerization though the property of selective reflection is retained. After the polymerization of the AA in the (E-CE)C/AA liquid crystalline solutions, the wavelength of the selective reflection of the cholesteric phase shifts to shorter wavelength direction and the selectivity and the intensity of the reflection are also decreased. The blue shift of selective reflection wavelength is caused by the decrease of the cholesteric pitch. The shift of the selective reflection wavelength and the variation and the variation ratio of the pitch of the cholesteric phase decrease with increasing the concentration of the (E-CE)C/AA cholesteric liquid crystalline solution. Though the vivid color of low molecular weight (E-CE)C/AA cholesteric liquid crystalline solution was lost after polymerization, lamellar structure of the slices of the composite is observed in the TEM shows that the cholesteric structure is also retained. The variation ratio of the cholesteric pitch after polymerization is not linear to the polymerization volume shrinkage ratio of the solvent monomer and the concentration of the solution though it is concerned with them. The variation ratio of the cholesteric pitch after polymerization gets smaller with decreasing the polymerization temperature. So decreasing the polymerization temperature is of great advantage to decrease the variation ratio of the cholesteric pitch after polymerization.