Thin film composite (TFC) membranes represent a highly promising platform for efficient nanofiltration (NF) processes. However

the improvement in permeance is impeded by the substrates with low permeances. Herein

highly permeable gradient phenolic membranes with tight selectivity are used as substrates to prepare TFC membranes with high permeances by the layer-by-layer assembly method. The negatively charged phenolic substrates are alternately assembled with polycation polyethylenimine (PEI) and polyanion poly(acrylic acid) (PAA) as a result of electrostatic interactions

forming thin and compact PEI/PAA layers tightly attached to the substrate surface. Benefiting from the high permeances and tight surface pores of the gradient nanoporous structures of the substrates

the produced PEI/PAA membranes exhibit a permeance up to 506 L·m

-2

·h

-1

·MPa

-1

which is ~2-10 times higher than that of other membranes with similar rejections. The PEI/PAA membranes are capable of retaining 96.1% of negatively charged dyes following the mechanism of electrostatic repulsion. We demonstrate that the membranes can also separate positively and neutr

ally charged dyes from water via other mechanisms. This work opens a new avenue for the design and preparation of high-flux NF membranes

which is also applicable to enhance the permeance of other TFC membranes.