CAS Key Laboratory of Engineering Plastics, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Repubic of China.
Biomacromolecules. 2011 Apr 11;12(4):1087-96. doi: 10.1021/bm101426p. Epub 2011 Mar 1.
Liquid crystalline (LC) phase transition and gel-sol transition in the solutions of microcrystalline cellulose (MCC) and ionic liquid (1-ethyl-3-methylimidazolium acetate, EMIMAc) have been investigated through a combination of polarized optical microscope (POM) observation and rheological measurements. Molecular LC phase forms at the 10 wt % cellulose concentration, as observed by POM, whereas the critical gel point is 12.5 wt % by rheological measurements according to the Winter and Chambon theory, for which the loss tangent, tan δ, shows frequency independence. Dramatic decreases of G' and G'' in the phase transition temperature range during temperature sweep are observed due to disassembling of the LC domain junctions. The phase diagram describing the LC phase and gel-sol transitions is obtained and the associated mechanisms are elucidated. A significant feature shown in the phase diagram is the presence of a narrow lyotropic LC solution region, which potentially has a great importance for the cellulose fiber wet spinning.
通过偏光显微镜（POM）观察和流变学测量相结合的方法，研究了微晶纤维素（MCC）和离子液体（1-乙基-3-甲基咪唑醋酸盐，EMIMAc）溶液中的液晶（LC）相转变和凝胶-溶胶转变。通过 POM 观察到，在 10wt%纤维素浓度下形成分子 LC 相，而根据 Winter 和 Chambon 理论，通过流变学测量得到的临界凝胶点为 12.5wt%，此时损耗角正切，tan δ，表现出频率独立性。在温度扫描过程中，由于 LC 畴界的解体，在相转变温度范围内观察到 G'和 G''的急剧下降。获得了描述 LC 相和凝胶-溶胶转变的相图，并阐明了相关机制。相图中一个显著的特征是存在一个狭窄的溶致液晶溶液区域，这对于纤维素纤维湿法纺丝具有重要意义。
