Molecular design of cellulosic thermotropic liquid crystals

从前一阶段的研究结果来看，为了研究纤维素液晶的结构与性能之间的关系，建立纤维素的合成方法是必不可少的。目前，在纤维素的2位或3位上引入特定区域的所需官能团是不可能的，但这可能通过纤维素的化学合成方法实现。我们于去年建立了化学合成纤维素的方法。今年，我们首先研究了取代基对聚合反应的影响，以阐明反应机理。研究发现，3- o-苄基对于立体和区域规则性是必不可少的，2- o-戊基对于区域特异性聚合是必不可少的。我们还成功地用dp20分步合成了纤维素二糖。因此，建立了生产区域特异性取代纤维素衍生物的方法。然后以合成2-丙基纤维素为例。因此，表明本合成方法可用于得到2- o -烷基，也可能是2-酰化纤维素衍生物。研究了2-丙基纤维素的溶解度和热行为，得到了几个有趣的发现。从而建立了积累纤维素液晶性质基础知识的方法。

From the results of this former research period, it was found that it is indispensable to establish the synthetic method for cellulose for investigating the relationship between structure and property of cellulosic liquid crystals. At present, the regiospecific introduction of the desired functional groups into the 2-or 3-position of cellulose is impossible, but this may be possible by the chemical synthetic method of cellulose. We established the chemical synthetic method cellulose in last year. In this year, we first of all investigated the substituent effect on the polymerization to clarify the reaction mechanism. It was found that 3-O-benzyl group is indispensable for the stereo-and regioregularity, and 2-O-pivaloyl group for regiospecific polymerization. We also succeeded in the stepwise synthesis of celloeicosaose with DP 20. Thus, the method yielding regiospecific substituted cellulose derivatives was established. Then, 2-propyl cellulose was first synthesized as an example. Consequently, it is indicated that the present synthetic method is useful for getting 2-O-alkyl and, probably, also 2-acylated cellulose derivatives. The solubility and thermal behavior of 2-propyl cellulolse were examined resulting several interesting findings. Thus the method for accumulating basic knowledge about cellulosic liquid crystalline properties was established.