Abstract
Graphene oxide (GO)-based membranes hold great promise for revolutionizing nanofiltration, thanks to their seamless water transport and efficient ion and molecular sieving capabilities. However, challenges such as membrane disintegration under high pressure and nanochannel swelling due to water intercalation hinder their upscaling. In this study, we addressed these issues by aligning GO-based liquid crystals through shear forces and stabilizing their stacking using a sequential interpenetrating polymeric network (IPN) via electrostatic anchorage. This approach retained long-range order through nanoconfinement. By carefully selecting starting materials for the IPN, such as dopamine and GO liquid crystals, we achieved a nematic phase at extremely low concentrations, a feat not achievable with conventional methods. The resulting membranes were extensively characterized using microscopic and spectroscopic techniques, revealing pore sizes in the range of 7 nm facilitated by nanomaterial inclusion. These highly ordered and structurally robust membranes exhibited exceptional water flux (145 LMH) and long-term separation efficiency (> 97%) for monovalent and divalent salts, dyes, and antibiotics. Molecular dynamics simulations provided detailed insights into the ionic sieving mechanism of the GO-based IPN membranes. The MD simulations support that the water flux is reduced upon arresting the rGO-I sheets within IPN which scales with the concentration of rGO-I. In addition, this confinement at molecular length scales leads to a reduction in the number of ions residing within the membrane region, favouring retention within the feed region. These results well corroborate with the observed experimental evidence. Moreover, the membranes showed antifouling, chlorine tolerance, antibacterial properties, and cytocompatibility. They remained stable over repeated operational periods and endured a wide range of harsh environmental conditions without swelling. These resilient and robust membranes pave the way for large-scale membrane fabrication and sustainable water treatment.