Perpendicular Phase Separation in Confined Binary Liquids: Unveiling Novel Kinetics and Stabilization Mechanisms for Nanofilms

We investigated the dynamics of a binary mixture confined within van der Waals walls using molecular dynamics simulations. We discovered a novel phenomenon named perpendicular separations of two phases (PSTP). In the initial stage, central water molecules diffused, subsequently condensing symmetrically within the confinement's midplane. In the later stage, as water droplets nucleate and grow, the resin separates perpendicularly into two films due to the action of bubblers and vdW walls, resulting in a hollow nanochannel. The mechanisms and conditions underlying PSTP are discussed. The results indicate that the concentration (<i>C</i>) of resin in the middle region is linearly decreased with temporal power (<i>C</i>(<i>t</i>,<i>T</i>) ∝ <i>a</i>(<i>T</i>)<i>t</i>^1/3). We propose a new mechanism for stabilizing nanochannels and films: dynamic "soft pillars" that prevent Rayleigh-like instability. Our findings could shed light on the manufacture of nanofilms and organic nanochannels, which could help advance biodetection and energy fields.