Microphase separation of a miscible binary liquid mixture under confinement at the nanoscale

Recent experimental works suggested that the confinement into a cylindrical nanopore induced the microphase separation of a binary liquid, despite the miscible character of its bulk counterpart. A core-shell organization was evidenced such that one of the liquids was strongly anchored to the solid surface whereas the other was confined at the center of the pore. At the same time, a study based on atomistic simulations suggested a strong heterogeneity and the absence of a separation. In this work, by refining the solid-liquid interactions to qualitatively reproduce the experimental adsorption isotherms of both single liquids, the microphase separation and the core-shell structure are captured. By tuning the surface chemistry of the nanopore to mimic hydrophilic and hydrophobic confinement, we show that it is possible to control the structural characteristics of the core-shell structure.The molecular origin of the microphase separation is then ascribed to the strong hydrogen bonds and a commensurate arrangement between the confining material and both liquids.