Department of Bioscience and Bioinformatics, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Kawazu 680-4, Iizuka, Fukuoka 820-8502, Japan.
J Chem Phys. 2010 Jun 7;132(21):214902. doi: 10.1063/1.3447892.
We present a mean field theory to describe phase separations in mixtures of a low molecular-weight-liquid crystalline (LC) molecule and a rigid-rodlike polymer (rod) such as carbon nanotubes (CNTs) and LC polymers. By taking into account two orientational order parameters of the rod and the LC, we find three nematic phases (N(0),N(1),N(2)) on the temperature-concentration plane, depending on the attractive or repulsive interactions between the rod and the LC. We discuss the phase behavior of the systems where the rod and the LC are oriented to be parallel or perpendicular with each other and find that the phase diagrams of the parallel alignment are different from that of the perpendicular one. We predict the appearances of a lower critical solution temperature (LCST) and an upper one, a tricritical point, a critical point, and the first- and the second-order nematic-isotropic phase transitions. The theory can qualitatively describe the phase diagram with a LCST observed in a rod/LC mixture. We also predict a variety of phase separations in CNT/LC mixtures.
我们提出了一个平均场理论来描述低分子量液晶（LC）分子和刚性棒状聚合物（如碳纳米管（CNTs）和 LC 聚合物）混合物中的相分离。通过考虑棒和 LC 的两个取向序参量，我们在温度-浓度平面上发现了三种向列相（N(0)、N(1)、N(2)），这取决于棒和 LC 之间的吸引或排斥相互作用。我们讨论了棒和 LC 彼此平行或垂直取向的系统的相行为，并发现平行排列的相图与垂直排列的相图不同。我们预测了低临界溶液温度（LCST）和上临界温度、三叉点、临界点以及一级和二级向列-各向同性相变的出现。该理论可以定性地描述在棒/LC 混合物中观察到的具有 LCST 的相图。我们还预测了 CNT/LC 混合物中的各种相分离。
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