Hyperbranched Molecular Brush Membrane for Efficient and Antifouling Oil‐Water Emulsion Separation

ABSTRACT The treatment of oily wastewater is a critical challenge due to the limitations of conventional separation technologies in handling stable oil‐in‐water (O/W) emulsions. This study presents a hyperbranched polylysine (HBPL)‐based molecular brush membrane modified with tricarballylic acid (TCA) for efficient and antifouling O/W emulsion separation. The tailored carboxyl‐terminated hyperbranched architecture endowed the membrane with superhydrophilicity, underwater superoleophobicity, and a pronounced negative charge. Characterizations demonstrated that the modified membrane exhibits significantly enhanced separation efficiency and superior fouling resistance against both oil and protein contaminants. The exceptional performance is attributed to the synergistic effects of a robust hydration layer and the strong electrostatic repulsion provided by the hyperbranched molecular brush, which effectively minimize foulant adhesion. Furthermore, the membrane showed good chemical stability across a wide pH range. This work presents a feasible surface‐engineering strategy using hyperbranched molecular brushes to achieve high‐performance, durable membranes for challenging oily wastewater treatment.