Gebbie Matthew A, Smith Alexander M, Dobbs Howard A, Lee Alpha A, Warr Gregory G, Banquy Xavier, Valtiner Markus, Rutland Mark W, Israelachvili Jacob N, Perkin Susan, Atkin Rob
Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, USA.
Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK.
Chem Commun (Camb). 2017 Jan 19;53(7):1214-1224. doi: 10.1039/c6cc08820a.
Ionic liquids are pure salts that are liquid under ambient conditions. As liquids composed solely of ions, the scientific consensus has been that ionic liquids have exceedingly high ionic strengths and thus very short Debye screening lengths. However, several recent experiments from laboratories around the world have reported data for the approach of two surfaces separated by ionic liquids which revealed remarkable long range forces that appear to be electrostatic in origin. Evidence has accumulated demonstrating long range surface forces for several different combinations of ionic liquids and electrically charged surfaces, as well as for concentrated mixtures of inorganic salts in solvent. The original interpretation of these forces, that ionic liquids could be envisioned as "dilute electrolytes," was controversial, and the origin of long range forces in ionic liquids remains the subject of discussion. Here we seek to collate and examine the evidence for long range surface forces in ionic liquids, identify key outstanding questions, and explore possible mechanisms underlying the origin of these long range forces. Long range surface forces in ionic liquids and other highly concentrated electrolytes hold diverse implications from designing ionic liquids for energy storage applications to rationalizing electrostatic correlations in biological self-assembly.
离子液体是在环境条件下呈液态的纯盐。作为仅由离子组成的液体，科学界的共识是离子液体具有极高的离子强度，因此德拜屏蔽长度非常短。然而，世界各地实验室最近的几项实验报告了由离子液体隔开的两个表面之间相互作用的数据，这些数据揭示了明显的长程力，其起源似乎是静电性质的。已有证据表明，对于离子液体与带电表面的几种不同组合，以及溶剂中无机盐的浓缩混合物，都存在长程表面力。对这些力的最初解释，即离子液体可被视为“稀电解质”，存在争议，离子液体中长程力的起源仍是讨论的主题。在此，我们试图整理和研究离子液体中长程表面力的证据，识别关键的突出问题，并探索这些长程力起源的潜在机制。离子液体和其他高浓度电解质中的长程表面力具有广泛的影响，从为储能应用设计离子液体到解释生物自组装中的静电相关性。
