Tailoring Robust 2D Nanochannels by Radical Polymerization for Efficient Molecular Sieving

Two-dimensional (2D) nanochannels have demonstrated outstanding performance for sieving specific molecules or ions, owing to their uniform molecular channel sizes and interlayer physical/chemical properties. However, controllably tuning nanochannel spaces with specific sizes and simultaneously achieving high mechanical strength remain the main challenges. In this work, the inter-sheet gallery d-spacing of graphene oxide (GO) membrane is successfully tailored with high mechanical strength via a general radical-induced polymerization strategy. The introduced amide groups from N-Vinylformamide significantly reinforce the 2D nanochannels within the freestanding membranes, resulting in an ultrahigh tensile strength of up to 105 MPa. The d-spacing of the membrane is controllably tuned within a range of 0.799-1.410 nm, resulting in a variable water permeance of up to 218 L m^-2 h^-1 bar^-1 (1304% higher than that of the pristine GO membranes). In particular, the tailored membranes demonstrate excellent water permeance stability (140 L m^-2 h^-1 bar^-1) in a 200-h long-term operation and high selectivity of solutes under harsh conditions, including a wide range of pH from 4.0 to 10.0, up to a loading pressure of 12 bar and an external temperature of 40 °C. This approach comprehensively achieves a balance between sieving performance and mechanical strength, satisfying the requirements for the next-generation molecular sieving membranes.