Midya Jiarul, Egorov Sergei A, Binder Kurt, Nikoubashman Arash
Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany.
Department of Chemistry, University of Virginia, McCormick Road, Charlottesville, Virginia 22904-4319, USA.
J Chem Phys. 2019 Jul 21;151(3):034902. doi: 10.1063/1.5110393.
The interplay of nematic order and phase separation in solutions of semiflexible polymers in solvents of variable quality is investigated by density functional theory (DFT) and molecular dynamics (MD) simulations. We studied coarse-grained models, with a bond-angle potential to control chain stiffness, for chain lengths comparable to the persistence length of the chains. We varied both the density of the monomeric units and the effective temperature that controls the quality of the implicit solvent. For very stiff chains, only a single transition from an isotropic fluid to a nematic is found, with a phase diagram of "swan-neck" topology. For less stiff chains, however, also unmixing between isotropic fluids of different concentration, ending in a critical point, occurs for temperatures above a triple point. The associated critical behavior is examined in the MD simulations and found compatible with Ising universality. Apart from this critical behavior, DFT calculations agree qualitatively with the MD simulations.
通过密度泛函理论（DFT）和分子动力学（MD）模拟，研究了半柔性聚合物在不同质量溶剂中的溶液中向列相序和相分离之间的相互作用。我们研究了粗粒化模型，该模型具有控制链刚度的键角势，链长与链的持久长度相当。我们改变了单体单元的密度和控制隐式溶剂质量的有效温度。对于非常刚性的链，只发现从各向同性流体到向列相的单一转变，其相图具有“天鹅颈”拓扑结构。然而，对于刚性较小的链，在高于三相点的温度下，不同浓度的各向同性流体之间也会发生不混溶，并在临界点结束。在MD模拟中研究了相关的临界行为，发现其与伊辛普适性兼容。除了这种临界行为外，DFT计算在定性上与MD模拟一致。
