"Rheology of Entangled Polyelectrolyte Solutions
"Rheology of Entangled Polyelectrolyte Solutions
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DOI：
10.1021/acs.macromol.0c02437
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发表时间：
2021-01-25
期刊：
影响因子：
5.5
通讯作者：
Colby, Ralph H.
中科院分区：
文献类型：
--
作者：
Han, Aijie;Colby, Ralph H.
聚电解质溶液动力学已被仔细研究实验和理论上的非纠缠的解决方案，并认为是合理的理解。虽然已经提出了理论模型的纠缠双溶液，有有限的实验数据公布，以证明任何理解的纠缠双溶液流变学。在此，我们研究了纠缠的近单分散仔细透析的聚苯乙烯磺酸铯（M-n = 2.83 × 10（6）g/mol）的水，无水乙二醇（T-g = -95 ℃）和无水甘油（T-g = -80 ℃）的无盐溶液，使用旋转流变仪和X射线散射，以确定相关长度。对于甘油溶液，发现时间-温度叠加在25和-5 ° C之间起作用，在宽频率范围内产生甘油溶液的线性粘弹性（LVE）响应。在缩放预测预期纠缠的浓度下，LVE响应似乎未纠缠（无橡胶态平台），表明低估了缠结浓度c（e）在缠结溶液中的较高浓度下，以甘油中的储能模量和损耗模量的两个交叉点的比率（tau（rep）/tau（e））测量的橡胶态平台宽度为c（4），这表明聚电解质溶液在缠结浓度范围内表现得像中性聚合物溶液。比较了四种计算缠结浓度的方法，它们的相对排序与中性聚合物溶液的排序相似。
Polyelectrolyte solution dynamics have been carefully studied experimentally and theoretically for unentangled solutions and thought to be reasonably well understood. While theoretical models have been proposed for entangled polyelectrolyte solutions, there have been limited experimental data published to justify any understanding of entangled polyelectrolyte solution rheology. Herein, we study entangled nearly monodisperse carefully dialyzed cesium polystyrene sulfonate (M-n = 2.83 x 10(6) g/mol) solutions without salt in water, anhydrous ethylene glycol (T-g = -95 degrees C), and anhydrous glycerol (T-g = -80 degrees C) using rotational rheometry and X-ray scattering to determine the correlation length. For the glycerol solutions, time-temperature superposition was found to work between 25 and -5 degrees C, yielding linear viscoelastic (LVE) response of polyelectrolyte solutions over a wide frequency range. At concentrations where scaling predictions expect entanglements, the LVE response appears unentangled (no rubbery plateau), suggesting an underestimation of the entanglement concentration c(e) At higher concentrations in entangled solutions, the rubbery plateau width measured as the ratio of the two crossing points of storage and loss moduli (tau(rep)/tau(e)) in glycerol scales as c(4), suggesting that polyelectrolyte solutions behave like solutions of neutral polymers in the entangled concentration regime. Four methods for evaluating entanglement concentration are compared, and their relative orderings are similar to those of neutral polymer solutions.