Metal ion coordination reconstruction: A facile strategy for fabricating permeance-enhanced acid-resistant polyurea nanofiltration membranes

Coordination-induced reconstruction enables high-flux PU NF membranes. • Zr 4+ selectively disrupts hydrogen-bonding networks in PU layer. • Spatial reconstruction creates free volume while preserving selectivity. • 21% higher permeance with >95% rejection under acidic conditions. • Decouples permeability–stability trade-off via simple post-modification. Polyurea membranes exhibit exceptional acid-base tolerance due to their densely cross-linked structure and extensive hydrogen-bonding network, making them attractive for separations under extreme pH conditions. However, the tightly associated network also leads to limited free volume, resulting in low water permeability that hinders practical applications. Herein, we report a permeance-enhanced polyurea nanofiltration membrane fabricated via coordination-induced structural reconstruction. By introducing Zr 4+ into the polyurea network, coordination interactions with urea groups partially disrupt interchain hydrogen bonding, leading to network loosening and additional free volume. As a result, the water permeance is increased by 21% without compromising selectivity. Meanwhile, incorporation of Zr 4+ enhances membrane hydrophilicity and surface positive charge, which therefore improves antifouling properties and promotes the rejection of heavy metal ions. Importantly, the reconstructed membrane retains excellent acid resistance, maintaining a stable salt rejection above 95% over 720 h. This work provides a simple yet effective strategy to overcome the permeability-stability trade-off in polyurea membranes and offers new insights into coordination-mediated regulation of polymer network structures for high-performance separations under harsh conditions. Download: Download high-res image (175KB) Download: Download full-size image