Hydrophobic materials for hydrophobic membrane engineering

Hydrophobic materials have become increasingly important for separation technologies operating under humid or chemically aggressive conditions, where conventional membranes often suffer from performance degradation. This review summarizes recent advances in hydrophobic membranes based on fluoropolymers, graphitic materials, zeolites, and porous crystalline frameworks, including metal–organic frameworks (MOFs), covalent organic frameworks (COFs), and hydrogen-bonded organic frameworks (HOFs). The roles of surface hydrophobicity, pore structure, and interfacial interactions in controlling transport, selectivity, and stability are critically discussed across applications in water treatment, organic solvent nanofiltration, gas separation, air purification, and energy-related systems. Representative examples highlight how hydrophobic interfaces mitigate water-induced swelling, pore blocking, and competitive adsorption, thereby enabling stable and efficient separations. Despite substantial progress, challenges remain in scalable fabrication, long-term stability, and cost-effective production, particularly for framework-based membranes. Future directions toward hybrid architectures, defect and interface engineering, and scalable processing are outlined to facilitate the translation of hydrophobic membrane materials into industrially relevant separation technologies.