Tuning the Solution Viscosity of Ionic-Liquid-Based Polyelectrolytes with Solvent Dielectric Constants via the Counterion Condensation
Tuning the Solution Viscosity of Ionic-Liquid-Based Polyelectrolytes with Solvent Dielectric Constants via the Counterion Condensation
复制标题
通过反离子缩合调节具有溶剂介电常数的离子液体基聚电解质的溶液粘度
DOI：
10.1021/acs.macromol.2c01405
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发表时间：
2022
期刊：
影响因子：
5.5
通讯作者：
Maeda Yasushi
中科院分区：
文献类型：
--
作者：
Matsumoto Atsushi;Ukai Ryosuke;Osada Hiroto;Sugihara Shinji;Maeda Yasushi
基于离子液体的聚电解质或聚合离子液体（PIL）是具有离子液体的有利性质的一类特殊的聚电解质。以往的研究发现，静电相互作用，因此解离的抗衡离子的数量控制的构象和动力学的PIL链在溶液中。本文通过测量一系列非离子良溶剂（介电常数从四氢呋喃的7.9到N-甲基甲酰胺的178）中的剪切粘度，研究了溶剂介电常数ε罗恩对模型PIL聚（1-丁基-3-乙烯基咪唑双（三氟甲磺酰基）酰亚胺）（PC 4-TFSI）有效电荷分数的影响。当PC 4-TFSI单体的摩尔浓度cp一定时，比粘度η sp随εr的减小而单调减小。在半稀态非纠缠区，高ε r时ηsponcpin溶剂的依赖性遵循无盐聚电解质在良溶剂中的ηsp（ε cp 0.5）标度律，但随着ε r的减小，其标度关系逐渐向电荷中性聚合物在良溶剂中的ηsp（ε cp 1.3）标度律移动。此外，通过加入离子液体作为盐离子屏蔽PC 4-TFSI链上的电荷，不同ε r的η自旋溶剂的依赖性下降到单一曲线上。这些结果表明，PC 4-TFSI链上的有效电荷分数随εr的减小而减小，与Manning反离子凝聚模型的预测趋势一致.因此，我们证明了反离子缩合发生在PIL解决方案，表明有能力控制PIL解决方案的性质，简单地通过改变溶剂的介电常数。由于PIL最近引起了广泛的关注，广泛的应用于电池，分子分离和抗菌，我们的研究结果可以提供有用的信息PIL解决方案的流变性能，优化PIL的加工操作，从而PIL为基础的材料设计与改进的系统性能。
Ionic-liquid-based polyelectrolytes, or polymerized ionic liquids (PILs), are a special class of polyelectrolytes having advantageous properties of ionic liquids. Previous studies have found that the electrostatic interaction and therefore the number of dissociated counterions govern the conformation and dynamics of PIL chains in solutions. Herein, we investigate the effect of the solvent dielectric constant εron the effective charge fractionfefffor a model PIL, poly(1-butyl-3-vinylimidazolium bis(trifluoromethanesulfonyl)imide) (PC4-TFSI), by measuring the shear viscosity of the PC4-TFSI in a series of non-ionic good solvents with dielectric constants ranging from 7.9 for tetrahydrofuran to 178 forN-methylformamide. For a given molar concentrationcpof PC4-TFSI monomers, the specific viscosity ηspdecreases monotonically with decreasing εr. In the semidilute unentangled regime, the dependence of ηsponcpin solvents at high εrfollows the scaling law of ηsp(∝cp0.5) for salt-free polyelectrolytes in good solvents, but its scaling relationship gradually shifts toward the scaling law of ηsp(∝cp1.3) for charge neutral polymers in good solvents as εris decreased. Moreover, thecpdependence of ηspin solvents having different εrfalls onto a single curve by adding an ionic liquid as salt ions to screen the charges on PC4-TFSI chains. These results indicate that the effective charge fraction on PC4-TFSI chains decreases with decreasing εr, in good agreement with the predicted trend by the Manning counterion condensation model. As a result, we demonstrate that the counterion condensation takes place in PIL solutions, indicating an ability to control the properties of PIL solutions simply by changing the solvent dielectric constant. Because PILs have recently attracted significant attention with a wide range of applications for batteries, molecular separations, and antimicrobial, our results can provide useful information about the rheological properties of PIL solutions, optimizing processing operations for PILs and thus PIL-based material design with improved system performance.