Ionic association and Wien effect in 2D confined electrolytes Toquer, Damien Bocquet, Lydéric Robin, Paul ; https://orcid.org/0000-0002-5728-9189 ddc:540 Recent experimental advances in nanofluidics have allowed to explore ion transport across molecular-scale pores, in particular, for iontronic applications. Two-dimensional nanochannels—in which a single molecular layer of electrolyte is confined between solid walls—constitute a unique platform to investigate fluid and ion transport in extreme confinement, highlighting unconventional transport properties. In this work, we study ionic association in 2D nanochannels, and its consequences on non-linear ionic transport, using both molecular dynamics simulations and analytical theory. We show that under sufficient confinement, ions assemble into pairs or larger clusters in a process analogous to a Kosterlitz–Thouless transition, here modified by the dielectric confinement. We further show that the breaking of pairs results in an electric-field dependent conduction, a mechanism usually known as the second Wien effect. However the 2D nature of the system results in non-universal, temperature-dependent, scaling of the conductivity with electric field, leading to ionic coulomb blockade in some regimes. A 2D generalization of the Onsager theory fully accounts for the non-linear transport. These results suggest ways to exploit electrostatic interactions between ions to build new nanofluidic devices. AIP Publishing 2025 info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/19279 https://research-explorer.ista.ac.at/download/19279/19290 Toquer D, Bocquet L, Robin P. Ionic association and Wien effect in 2D confined electrolytes. <i>Journal of Chemical Physics</i>. 2025;162(6). doi:<a href="https://doi.org/10.1063/5.0241949">10.1063/5.0241949</a> eng info:eu-repo/semantics/altIdentifier/doi/10.1063/5.0241949 info:eu-repo/semantics/altIdentifier/issn/0021-9606 info:eu-repo/semantics/altIdentifier/e-issn/1089-7690 info:eu-repo/semantics/altIdentifier/wos/001421300300001 info:eu-repo/semantics/altIdentifier/arxiv/2410.03316 info:eu-repo/semantics/altIdentifier/pmid/39932241 info:eu-repo/semantics/openAccess