The nonequilibrium properties of uniformly charged linear polymers in the presence of explicit counterions under shear flow are studied by coarse-grained mesoscale hydrodynamics simulations. The conformational properties of the polyelectrolyte (PE) are quantified by the gyration tensor, the distribution of the end-to-end distance, and alignment with the flow, which display rather universal behavior for small and moderate electrostatic interaction strengths in the regime of condensed counterions. In the limit of strong counterion condensation, shear flow leads to a globule-coil transition and polymer stretching, associated with an increase of the effective PE charge. The polyelectrolytes exhibit a pronounced tumbling motion with cyclic stretched and collapsed conformations. The average tumbling-time period decreases with increasing shear rate by a power-law with the exponent − 2 / 3 for PEs in the coiled state. The tumbling time exhibits a plateaulike regime over nearly a decade of shear rates for PEs in the globular state. In addition, we identify various characteristic PE structures under flow in the globule and coil limits determined by the condensed counterions.

中文翻译：

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聚电解质的流动驱动转变

通过粗粒度中尺度流体动力学模拟研究了在剪切流下存在显式反离子的情况下均匀带电线性聚合物的非平衡特性。聚电解质 (PE) 的构象特性通过旋转张量、端到端距离的分布以及与流动的对齐进行量化，这些特性在凝聚态下对小和中等静电相互作用强度显示出相当普遍的行为。反离子。在强反离子凝聚的极限下，剪切流导致球状线圈转变和聚合物拉伸，与有效 PE 电荷的增加相关。聚电解质表现出明显的翻滚运动，具有循环拉伸和折叠构象。对于卷曲状态的PE，平均翻滚时间周期随着剪切速率的增加而减少，其指数为- 2 / 3。对于球形状态的 PE，翻滚时间在近十年的剪切速率下表现出类似平台的状态。此外，我们确定了由凝聚的反离子确定的球体和线圈限制中流动下的各种特征 PE 结构。