Artificial Water Channels Form Precursors to Sponge-Like Aggregates in Water–Ethanol Mixtures

Abstract

Self-assembled artificial water channels (AWCs) are reshaping current water desalination technologies. Recently, the improvements achieved by incorporating hydrophilic compounds into polyamide membranes (PA) at the interface were confirmed experimentally. However, the determination of the nanoscale structures of AWCs remains unclear. An important step in the preparation of PA membranes is the solubilization of a colloidal suspension of the solid phase in a water–ethanol mixture. We perform molecular dynamics simulations to study the nanoscale structures of AWC aggregates. We characterize the size and shape of the aggregates at several key locations in the ternary phase diagram. The role of ethanol in the formation of the interface between the solvent and the solute phase is highlighted. We found that the structure of the aggregates formed in the ternary solution resembled the disordered sponge-like structures observed when AWCs were inserted into lipid membranes. Such permeable sponge architectures allow the passage of water despite their noncrystalline organization and were previously shown to be consistent with AWC permeation measurements in membrane environments.

Widom Line in Supercritical Water in Terms of Changes in Local Structure: Theoretical Perspective

“…The algorithm is suitable for data with varying densities and can identify density domains of arbitrary shapes. This approach was used previously to sample the density fluctuation in Ar, in polymers, , during crystallization, in aqueous solutions, during lipid mixing and in phase and interface determination . DBSCAN requires two main parameters, i.e., the spatial extent around the probe particle, defined by the distance threshold, r t , and the target number of neighbors within this threshold distance, n t .…”