Microrheological Approach for Probing the Entanglement Properties of Polyelectrolyte Solutions
Microrheological Approach for Probing the Entanglement Properties of Polyelectrolyte Solutions
复制标题
探测聚电解质溶液缠结特性的微流变学方法
DOI：
10.1021/acsmacrolett.1c00563
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发表时间：
2021
影响因子：
7.015
通讯作者：
Shen Amy Q.
中科院分区：
文献类型：
--
作者：
Matsumoto Atsushi;Zhang Chi;Scheffold Frank;Shen Amy Q.
聚电解质溶液的纠缠动力学和粘弹性仍然是当前研究的热点。以前的研究已经报道了与Dobrynin从Doi-Edwards(DE)管模型得到的纠缠聚合物的比例预测相比较的相互矛盾的实验结果。在这里，我们结合经典的整体剪切流变学和扩散波谱微观流变学，研究了含高相对分子质量聚苯乙烯磺酸钠的半稀缠结(SE)溶液的关键粘弹性参数(比粘度ηSp，平台模数Ge，缠结链的旋转时间与唤醒时间之比τ/τe)与聚合物浓度之间的关系。我们的实验测量得到Ge∝c1.51±0.04，与Dobrynin模型预测的无盐聚电解质SE溶液的Ge∝c1.5的标度一致，表明静电相互作用影响了聚电解质SE溶液的粘弹性。另一方面，ηsp∝c2.56±0.04和τrep/τe∝c1.82±0.28的标度指数与Dobrynin的模型预测(∝c1.5)之间存在偏差，这可能是因为Dobrynin的标度模型没有考虑到中性聚合物SE溶液中存在的轮廓长度波动、约束释放和溶剂动力学滞后等机制。结果表明，DWS是研究聚电解质溶液纠缠动力学的有力流变学工具。本研究中得到的标度关系为长期以来关于聚电解质溶液纠缠动力学的争论提供了新的见解。
The entanglement dynamics and viscoelasticity of polyelectrolyte solutions remain active research topics. Previous studies have reported conflicting experimental results when compared to Dobrynin’s scaling predictions derived from the Doi–Edwards (DE) tube model for entangled polymers. Herein, by combining classical bulk shear rheometry with diffusing wave spectroscopy (DWS) microrheometry, we investigate how the key viscoelastic parameters (the specific viscosity ηsp, the plateau modulusGe, and the ratio of the reptation time to the Rouse time of an entanglement strand τrep/τe) depend on the polymer concentration for semidilute entangled (SE) solutions containing poly(sodium styrenesulfonate) with high molecular weight. Our experimental measurements yieldGe∝c1.51±0.04, in good agreement with the scaling ofGe∝c1.5predicted by Dobrynin’s model for salt-free polyelectrolyte SE solutions, suggesting that the electrostatic interaction influences the viscoelastic properties of polyelectrolyte SE solutions. On the other hand, the deviation in the scaling exponent for ηsp∝c2.56±0.04and τrep/τe∝c1.82±0.28is observed between our DWS experiments and Dobrynin’s model prediction (∝c1.5), likely due to the fact that Dobrynin’s scaling model does not account for mechanisms such as the contour length fluctuation, the constraint release, and the retardation of solvent dynamics, which are known to occur for SE solutions of neutral polymers. Our results demonstrate that DWS serves as a powerful rheological tool to study the entanglement dynamics of polyelectrolyte solutions. The scaling relationships obtained in this study provide new insights to the long-standing debate on the entanglement dynamics of polyelectrolyte solutions.