Self-induced hydrodynamic coil-stretch transition of active polymers
Self-induced hydrodynamic coil-stretch transition of active polymers
复制标题
活性聚合物的自诱导流体动力线圈拉伸转变
DOI：
10.1103/physreve.105.014608
复制
发表时间：
2022
影响因子：
2.4
通讯作者：
Saintillan, David
中科院分区：
文献类型：
--
作者：
Mahajan, Achal;Saintillan, David
我们分析了一个活性聚合物模型的构象动力学和统计性质。该聚合物被描述为一个自由连接的头杆链，受随机有源力偶极子的影响，偶极子作用于悬浮溶剂，在那里它们驱动长期流体流动。利用无约束域中孤立链的朗格万模拟，我们展示了活性流动与聚合物构象的耦合如何导致涌现动力学。具有可收缩偶极子的系统的行为类似于被动布朗链，由于偶极流而增强波动。然而，在具有可伸缩偶极子的系统中，我们的模拟揭示了一种主动的线圈-拉伸转变，即聚合物在其自身诱导的流体动力流动中自发展开和拉伸，并且我们根据无量纲活度参数来描述这种转变，将主动偶极子力与热波动进行比较。我们讨论了在拉伸流动中被动聚合物的经典线圈-拉伸过渡的背景下我们的发现，并用一个简单的主动三聚体动力学模型补充了我们的模拟。
We analyze the conformational dynamics and statistical properties of an active polymer model. The polymer is described as a freely jointed bead-rod chain subject to stochastic active force dipoles that act on the suspending solvent where they drive long-ranged fluid flows. Using Langevin simulations of isolated chains in unconfined domains, we show how the coupling of active flows with polymer conformations leads to emergent dynamics. Systems with contractile dipoles behave similarly to passive Brownian chains with enhanced fluctuations due to dipolar flows. In systems with extensile dipoles, however, our simulations uncover an active coil-stretch transition whereby the polymer spontaneously unfolds and stretches out in its own self-induced hydrodynamic flow, and we characterize this transition in terms of a dimensionless activity parameter comparing active dipolar forces to thermal fluctuations. We discuss our findings in the context of the classic coil-stretch transition of passive polymers in extensional flows and complement our simulations with a simple kinetic model for an active trimer.