Nacre-inspired MXene/polyetherimide membranes with ultra-low swelling for high-salinity organic wastewater treatment

MXene displays exceptional promise for water purification, owing to its versatile surface chemistry and favorable physicochemical properties. However, its separation performance is substantially hindered by intercalation-induced swelling. Here, inspired by the “brick-and-mortar” structure of nacre, nacre-like nanocomposite membranes are developed through the co-assembly of MXene nanosheets (bricks) and polyetherimide (mortar). Leveraging MXene's unique properties, polyetherimide serves three pivotal functions: it acts as "spacer", precisely defines the interlayer spacing at ∼13.84 Å; it functions as "regulator", abundant hydrophobic groups regulate the microenvironment within the nanochannels; and it serves as "stabilizer", establishes robust non-covalent interactions with the MXene basal planes, thereby reinforcing channel integrity. Consequently, the resulting membranes exhibit outstanding stability in aqueous media, achieving a swelling ratio as low as 1.56%. Remarkably, after 1080 h of static water immersion, the membrane retained a relatively stable interlayer structure and separation performance, demonstrating prolonged aqueous stability. This bioinspired strategy provides critical insights for the rational design of structurally stable two-dimensional membranes.