Milchev Andrey, Egorov Sergei A, Midya Jiarul, Binder Kurt, Nikoubashman Arash
Institute for Physical Chemistry, Bulgarian Academia of Sciences, 1113 Sofia, Bulgaria.
Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany.
Polymers (Basel). 2021 Jul 11;13(14):2270. doi: 10.3390/polym13142270.
Mixtures of semiflexible polymers with a mismatch in either their persistence lengths or their contour lengths are studied by Density Functional Theory and Molecular Dynamics simulation. Considering lyotropic solutions under good solvent conditions, the mole fraction and pressure is systematically varied for several cases of bending stiffness κ (the normalized persistence length) and chain length . For binary mixtures with different chain length (i.e., NA=16, NB=32 or 64) but the same stiffness, isotropic-nematic phase coexistence is studied. For mixtures with the same chain length (N=32) and large stiffness disparity (κB/κA=4.9 to 8), both isotropic-nematic and nematic-nematic unmixing occur. It is found that the phase diagrams may exhibit a triple point or a nematic-nematic critical point, and that coexisting phases differ appreciably in their monomer densities. The properties of the two types of chains (nematic order parameters, chain radii, etc.) in the various phases are studied in detail, and predictions on the (anisotropic) critical behavior near the critical point of nematic-nematic unmixing are made.
通过密度泛函理论和分子动力学模拟研究了持久长度或轮廓长度不匹配的半柔性聚合物混合物。考虑到在良溶剂条件下的溶致液晶溶液，对于几种弯曲刚度κ（归一化持久长度）和链长的情况，系统地改变了摩尔分数和压力。对于具有不同链长（即NA = 16、NB = 32或64）但相同刚度的二元混合物，研究了各向同性 - 向列相共存情况。对于具有相同链长（N = 32）和较大刚度差异（κB/κA = 4.9至8）的混合物，同时出现了各向同性 - 向列相分离和向列 - 向列相分离。发现相图可能呈现一个三相点或一个向列 - 向列相临界点，并且共存相的单体密度有明显差异。详细研究了各相中两种类型链的性质（向列序参数、链半径等），并对向列 - 向列相分离临界点附近的（各向异性）临界行为进行了预测。
