Polyamide-poly (ionic liquid) reverse osmosis membrane with manifold excellent performance prepared via bionic capillary network for seawater desalinization

The trade-off between permeability and selectivity is a substantial impediment to the application of polyamide (PA) reverse osmosis (RO) membranes. To overcome this problem, we prepared a high-performance PA-poly(ionic liquid) (PIL, poly(1-vinyl-3-butylimidazolium tetrafluoroborate)) RO membrane by two-step polymerization. An interpenetrating network structure of PA-PIL with water transmembrane channels was constructed based on hydrophilic PIL chains, similar capillary networks scattered throughout bodily tissue. Compared to the primary RO membrane, the water contact angle of the PA-PIL membrane decreased from 67.7° to 40.1°, and the water flux increased by nearly 50% at 15.5 bar. The membrane benefited from the electrostatic repulsion between the imidazole cations and sodium ions , and the NaCl rejection rates increased from 97.3% to 99.2%. More importantly, the PA-PIL membrane exhibited excellent antifouling and antimicrobial properties and long-term separation stability owing to the antibacterial activities of the imidazole structure in PIL and the smooth membrane surface. The excellent performance of PA-PIL modified membranes make them potentially very useful in seawater desalinization and other areas.