One-step enhancement of solvent transport, stability and photocatalytic properties of graphene oxide/polyimide membranes with multifunctional cross-linkers

The practical application of graphene oxide (GO)/polymer composite membranes requires addressing the poor long-term stability caused by exfoliation of GO laminates from the substrate, solvent dissolution of the substrate and fouling by organic pollutants. This study describes the concurrent cross-linking of GO laminates, a polyimide substrate and their interface through a single filtration step with multifunctional triethylenetetramine (TETA). The new strategy features the following advantages: (1) the improved free volume and tunable charge characteristic of GO laminates lead to higher acetonitrile permeance with precise molecular sieving properties over state-of-art organic solvent nanofiltration (OSN) membranes; (2) the covalent bonding formed at the GO/polyimide interface and polyimide substrate endows the membrane with significantly enhanced stability in harsh environments; (3) the photocatalytic properties hold great potential for fouling reduction and dye decolorization.