Free‐Standing Amphiphilic Organic Membrane toward Ultrafast and Efficient Demulsification

Abstract Conventional oil‐water separation techniques, such as absorption and flocculation, are still widely employed despite their high energy demands and limited separation efficiency. Membrane‐based separation has emerged as a promising alternative; however, its practical implementation is often hindered by severe fouling caused by oil and surfactants. In this regard, the first free‐standing, amphiphilic organic membrane (AOM‐1) is judiciously designed and interfacially fabricated for the demulsification of surfactant‐stabilized water‐in‐oil. AOM‐1 is composed of hydrophilic polyethylene glycol (PEG) – inspired core and hydrophobic alkyl chains, creating an oxymoronic structure that prevents fouling and offers excellent oil permeation even in the presence of surfactants. In comparison, a hydrophobic organic membrane (HOM‐1), lacking the PEG core, exhibits inferior performance. The AOM‐1 achieves a steady flow rate of ≈2550 L·m − 2 ·h − ¹, recyclability over five cycles, and a high separation capacity of ≈7.1 × 10 3 L·m − 2 , outperforming HOM‐1 (≈1.6 × 10 3 L·m − 2 ). Mechanistic investigation using molecular dynamics simulations reveals nonpolar‐nonpolar interactions (−21.09 kJ mol −1 ) between surfactant and membrane, facilitating emulsion infiltration in HOM‐1, while the additional strong polar‐polar interactions in AOM‐1 (−137.70 kJ mol −1 ) prevent pore blockage. The large‐scale demulsification capability and antifouling nature with better recyclability of AOM‐1 open the avenue for exploring amphiphilic membranes as potential alternatives to traditional and energy‐intensive methods.