Polyelectrolytes (PE) are charged polymers in polar solvents. Classical scaling theories suggest that the viscosity $$ for semidilute unentangled PE solutions in $\theta$ solvents obeys the empirical Fuoss law $\eta \propto n_p^{1/2}$ in the “salt-free” regime, and $\eta \propto n_p^{5/4}$ in the regime affected by added salt, where the polymer concentration $n_p$ is defined as number of monomers per volume. However, recent experiments have also reported $\eta \propto n_p^{0.68}$ and $\eta \propto n_p^{0.91}$, which are at odds with the classical scaling theories. To rationalize the four distinct scaling laws, we probe the electrostatic energy per monomer under the influence of salt and their contributions to the viscosity of PE solutions. We identify four consecutive regimes dependent on the magnitude of the ratio of the polymer concentration $n_p$ to the salt concentration $n_s$, which capture the unexplained observations, and provide physical insights for the influence of salt contamination and added salt on the properties of both weakly and strongly charged semidilute unentangled PE solutions.

中文翻译：

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盐对聚电解质溶液粘度的影响

聚电解质（PE）是极性溶剂中的带电聚合物。经典的定标理论表明，半稀释无缠结PE溶液的粘度$$$\theta$ 溶剂遵守经验Fuoss定律 $\eta \propto {ñ}_p^{\mathrm{1个}/2}$ 在“无盐”制度下，以及 $\eta \propto {ñ}_p^{5/4}$ 在受添加盐影响的体系中，聚合物浓度 ${ñ}_p$定义为每体积的单体数量。但是，最近的实验也有报道$\eta \propto {ñ}_p^{0.68}$ 和 $\eta \propto {ñ}_p^{0.91}$，与经典的缩放理论不符。为了合理化四个不同的缩放定律，我们在盐的影响下探索每个单体的静电能及其对PE溶液粘度的影响。我们确定了四个连续的方案，具体取决于聚合物浓度比的大小${ñ}_p$ 盐浓度 ${ñ}_s$，它捕获了无法解释的观察结果，并为盐污染和添加盐对弱电荷和强电荷半稀释无缠结PE溶液的性能提供了物理见解。