Singh Manjesh K, Ilg Patrick, Espinosa-Marzal Rosa M, Spencer Nicholas D, Kröger Martin
Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
School of Mathematical and Physical Sciences, University of Reading, Reading RG6 6AX, UK.
Polymers (Basel). 2016 Jul 8;8(7):254. doi: 10.3390/polym8070254.
We have performed coarse-grained molecular-dynamics simulations on both flexible and semiflexible multi-bead-spring model polymer brushes in the presence of explicit solvent particles, to explore their tribological and structural behaviors. The effect of stiffness and tethering density on equilibrium-brush height is seen to be well reproduced within a Flory-type theory. After discussing the equilibrium behavior of the model brushes, we first study the shearing behavior of flexible chains at different grafting densities covering brush and mushroom regimes. Next, we focus on the effect of chain stiffness on the tribological behavior of polymer brushes. The tribological properties are interpreted by means of the simultaneously recorded density profiles. We find that the friction coefficient decreases with increasing persistence length, both in velocity and separation-dependency studies, over the stiffness range explored in this work.
我们在存在明确溶剂粒子的情况下，对柔性和半柔性多珠弹簧模型聚合物刷进行了粗粒度分子动力学模拟，以探索它们的摩擦学和结构行为。在弗洛里型理论中，可以很好地再现刚度和接枝密度对平衡刷高度的影响。在讨论了模型刷的平衡行为之后，我们首先研究了在覆盖刷状和蘑菇状区域的不同接枝密度下柔性链的剪切行为。接下来，我们关注链刚度对聚合物刷摩擦学行为的影响。通过同时记录的密度分布来解释摩擦学性质。我们发现，在这项工作所探索的刚度范围内，无论是在速度和分离依赖性研究中，摩擦系数都随着持久长度的增加而降低。
