Hefei National Laboratory for Physical Sciences at the Microscale, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, PR China.
Discipline of Chemistry and Physics, CSHEE, Murdoch University, 90 South St., Murdoch 6150, WA, Australia.
J Colloid Interface Sci. 2020 Nov 1;579:369-378. doi: 10.1016/j.jcis.2020.06.072. Epub 2020 Jun 20.
A detailed understanding of the influence of electrolytes on the conformation of polyelectrolyte chains is an important goal made challenging by the strong coupling between electrostatic interactions and chain conformation. This challenge is particularly evident at moderate to high salt concentrations where mean-field theories of electrolytes are no longer applicable and are therefore unable to predict the interactions between neutral or like charged surfaces that leads to re-entrant swelling of DNA and other polyelectrolytes at high salt concentrations. Recent developments arising from studies of surface forces in ionic liquids that have been extended to include a wide variety of monovalent electrolytes reveal a hitherto unknown increase in the electrostatic decay length at high electrolyte concentrations. We hypothesise that the re-entrant behaviour of polyelectrolytes is driven by an increasing electrostatic decay length with increasing electrolyte concentration.
We survey numerous experiments in the literature on re-entrant swelling and calculate the effect of ion pairing on the electrostatic decay length in concentrated electrolytes.
Re-entrant solubility is driven by an increasing electrostatic decay length at high salt concentrations and is universal across all polyelectrolytes.
深入了解电解质对聚电解质链构象的影响是一个重要目标，但由于静电相互作用和链构象之间的强耦合，这一目标具有挑战性。在中等至高盐浓度下，这一挑战尤为明显，因为电解质的平均场理论不再适用，因此无法预测中性或相似带电表面之间的相互作用，而这些相互作用会导致 DNA 和其他聚电解质在高盐浓度下发生再进入式溶胀。最近，从离子液体表面力研究中发展出来的理论已被扩展到包括各种单价电解质，揭示了在高电解质浓度下静电衰减长度迄今未知的增加。我们假设，聚电解质的再进入行为是由电解质浓度增加导致的静电衰减长度增加驱动的。
我们调查了文献中关于再进入溶胀的大量实验，并计算了离子配对对高浓度电解质中静电衰减长度的影响。
在高盐浓度下，再进入溶解度是由静电衰减长度的增加驱动的，并且在所有聚电解质中都是普遍存在的。
