Acid-triggered dynamic interlayer engineering enables high-permeance reverse osmosis membranes

An acid-triggered dynamic interlayer regulates interfacial polymerization. • A Schiff base interlayer serves as a controllable m -phenylenediamine reservoir. • Generated hydrochloric acid triggers imine hydrolysis and monomer release. • A wrinkled polyamide layer with abundant internal nanovoids is formed. • The membrane shows 2.6-fold higher permeance with 99.2% NaCl rejection. Reverse osmosis (RO) membranes are widely used in seawater desalination, brackish water desalination, and water reuse. However, their performance remains constrained by the intrinsic permeance-selectivity trade-off of conventional polyamide membranes. Herein, we present an acid-triggered dynamic interlayer strategy for regulating interfacial polymerization to fabricate RO membranes with high water permeance. A sacrificial Schiff-base interlayer was constructed by sequential deposition of 2,4,6-triformylphloroglucinol (Tp) on a polysulfone substrate, followed by reaction with m -phenylenediamine (MPD), thereby forming a dynamic imine network that served as an MPD reservoir. Upon contact with 1,3,5-benzenetricarbonyl trichloride, interfacial polymerization was initiated, during which HCl generated in situ catalyzed the hydrolysis of imine bonds and triggered localized release of MPD. This dynamic process perturbs the reaction-diffusion balance and promotes the formation of a highly crumpled polyamide layer with enlarged internal nanovoids, accompanied by an increase in surface roughness from 43.1 to 70.7 nm. As a result, the optimized membrane achieves a water permeance of 4.1 L m −2  h −1  bar −1 , representing a 2.6-fold increase over the pristine membrane, while maintaining a high NaCl rejection of 99.2%. Simulated acid-etching and triethylamine inhibition experiments further verify the critical role of the acid-triggered process in membrane structural evolution. Moreover, replacing Tp with 1,3,5-benzenetricarboxaldehyde produces similar morphological changes and performance enhancement, highlighting the generality of this strategy. This work establishes an effective approach for modulating polyamide growth through dynamic interlayer engineering and offers a promising route toward high-performance RO membranes for efficient water treatment. Download: Download high-res image (359KB) Download: Download full-size image