Srivastva Deepika, Nikoubashman Arash
Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany.
Polymers (Basel). 2018 May 29;10(6):599. doi: 10.3390/polym10060599.
Star-shaped polymers show a continuous change of properties from flexible linear chains to soft colloids, as the number of arms is increased. To investigate the effect of macromolecular architecture on the flow properties, we employ computer simulations of single chain and star polymers as well as of their mixtures under Poiseuille flow. Hydrodynamic interactions are incorporated through the multi-particle collision dynamics (MPCD) technique, while a bead-spring model is used to describe the polymers. For the ultradilute systems at rest, the polymers are distributed uniformly in the slit channel, with a weak dependence on their number of arms. Once flow is applied, however, we find that the stars migrate much more strongly towards the channel center as the number of arms is increased. In the star-chain mixtures, we find a flow-induced separation between stars and chains, with the stars located in the channel center and the chains closer to the walls. In order to identify the origin of this flow-induced partitioning, we conduct additional simulations without hydrodynamic interactions, and find that the observed cross-stream migration originates from a combination of wall-induced hydrodynamic lift forces and viscoelastic effects. The results from our study give valuable insights for designing microfluidic devices for separating polymers based on their architecture.
随着臂数的增加，星形聚合物呈现出从柔性线性链到软胶体的连续性质变化。为了研究大分子结构对流动性质的影响，我们采用计算机模拟方法，对单链聚合物、星形聚合物及其在泊肃叶流作用下的混合物进行模拟。通过多粒子碰撞动力学（MPCD）技术引入流体动力学相互作用，同时使用珠簧模型来描述聚合物。对于静止的超稀溶液体系，聚合物在狭缝通道中均匀分布，对其臂数的依赖性较弱。然而，一旦施加流动，我们发现随着臂数的增加，星形聚合物向通道中心的迁移更为强烈。在星形 - 链混合物中，我们发现流动会导致星形聚合物和链之间的分离，星形聚合物位于通道中心，而链更靠近壁面。为了确定这种流动诱导分离的起源，我们进行了无流体动力学相互作用的额外模拟，发现观察到的横向迁移源于壁面诱导的流体动力升力和粘弹性效应的组合。我们的研究结果为基于聚合物结构设计用于分离聚合物的微流体装置提供了有价值的见解。
