Scalable spray-UV fabrication of poly(vinyl alcohol)–charged covalent organic framework hybrid membranes for hypersaline desalination

Covalent organic frameworks (COF) with tunable functionality provide opportunities to engineer transport pathways and interfacial interactions in hybrid membranes. Here, we integrate three kinds of charged COF nanosheets with poly(vinyl alcohol) (PVA)-styrene pyridinium salt (SBQ) matrices via spray coating followed by ultraviolet (UV) crosslinking to construct pervaporation membranes for hypersaline desalination. Spray coating enabled homogeneous nanosheet dispersion and enhanced interfacial compatibility, as confirmed by reduced PVA crystallinity (XRD) and optimized free-volume characteristics (PALS). Three charged COF nanosheets, including neutral TpPa, positively charged TpPa-Py, and negatively charged TpPa-SO 3 H, introduced hydrogen-bonding and charge–dipole interactions at the interface, stabilizing the hybrid network and facilitating selective water transport. Among them, the PVA-SBQ-TpPa-SO 3 H membrane exhibited the highest performance, achieving 357.38 kg m −2  h −1 flux with 99.9 % rejection at 50 °C in 3.5 wt% NaCl. Stable operation was maintained in the presence of organic and inorganic foulants. Automated spray–UV processing further enabled A4-sized membranes with 307.12 kg m −2  h −1 flux and 99.9 % rejection, demonstrating practical scalability. This work highlights the interfacial chemistry and membrane processing method in advancing COF-based hybrid membranes.