Polyamide (PA)-based thin-film composite membranes exhibit enormous potential in water purification

owing to their facile fabrication

decent performance and desirable stability. However

the thick PA active layer with high transport resistance from the conventional interfacial polymerization hampers their applications. The controllable fabrication of a thin PA active layer is essential for high separation efficiency but still challenging. Herein

a covalent organic framework TpPa-1 interlayer was firstly deposited on a polyethersulfone (PES) substrate to reduce the thickness of PA active layer in interfacial polymerization. The abundant pores of TpPa-1 increase the local concentration of amine monomers by adsorbing piperazine molecules

while hydrogen bonds between hydrophilic groups of TpPa-1 and piperazine molecules slow down their diffusion rate. Arising from those synergetic effects

the PA active layer is effectively reduced from 200 nm to 120 nm. By optimizing TpPa-1 interlayer and PA active layer

the water flux of resultant membranes can reach 171.35 L·m

-2

·h

-1

·MPa

-1

which increased by 125.4% compared with

PA/PES membranes

while the rejection rates of sodium sulfate and dyes solution remained more than 90% and 99%

respectively. Our strategy may stimulate rational design of ultrathin PA-based nanofiltration membranes with high performances.