Shin Jaeoh, Cherstvy Andrey G, Kim Won Kyu, Zaburdaev Vasily
Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany.
Phys Chem Chem Phys. 2017 Jul 19;19(28):18338-18347. doi: 10.1039/c7cp02947k.
While the dynamics of polymer chains in equilibrium media is well understood by now, the polymer dynamics in active non-equilibrium environments can be very different. Here we study the dynamics of polymers in a viscous medium containing self-propelled particles in two dimensions by using Brownian dynamics simulations. We find that the polymer center of mass exhibits a superdiffusive motion at short to intermediate times and the motion turns normal at long times, but with a greatly enhanced diffusivity. Interestingly, the long time diffusivity shows a non-monotonic behavior as a function of chain length and stiffness. We analyze how the polymer conformation and the accumulation of self-propelled particles, and therefore the directed motion of the polymer, are correlated. At the point of maximal polymer diffusivity, the polymer has preferentially bent conformations maintained by the balance between the chain elasticity and the propelling force generated by the active particles. We also consider the barrier crossing dynamics of actively-driven polymers in a double-well potential. The barrier crossing times are demonstrated to have a peculiar non-monotonic dependence, related to that of the diffusivity. This effect can be potentially utilized for sorting polymers from solutions in in vitro experiments.
虽然目前人们已经很好地理解了聚合物链在平衡介质中的动力学，但在活性非平衡环境中的聚合物动力学可能会非常不同。在这里，我们通过布朗动力学模拟研究了聚合物在二维含自驱动粒子的粘性介质中的动力学。我们发现，聚合物质心在短到中等时间内呈现超扩散运动，而在长时间时运动变为正常扩散，但扩散率大大增强。有趣的是，长时间扩散率作为链长和刚度的函数呈现非单调行为。我们分析了聚合物构象与自驱动粒子的积累以及聚合物的定向运动之间的相关性。在聚合物扩散率最大的点，聚合物具有优先弯曲的构象，这是由链弹性与活性粒子产生的推进力之间的平衡所维持的。我们还考虑了在双阱势中主动驱动聚合物的势垒穿越动力学。结果表明，势垒穿越时间具有奇特的非单调依赖性，这与扩散率的非单调依赖性有关。这种效应在体外实验中可能潜在地用于从溶液中筛选聚合物。
