Nanoimprinted polyamide membranes for ultrafast and precise molecular sieving with low fouling.

Polyamide membranes with ultrahigh permeance and exceptional solute selectivity present a significant opportunity to reduce energy consumption in desalination, pharmaceutical purification, and solvent recovery. We report a nanomolding phase inversion strategy for constructing high-resolution pillar-array patterns on a nanofibrous Kevlar hydrogel support, enabling controlled interfacial polymerization (IP) of polyamide active layers with pillar-arrayed structures. The rigid polyamide layers preserve pillar textures under pressurized filtration, increasing permeable area, while the nanofibrous Kevlar regulates amine diffusion to enhance polyamide layer homogeneity. The resulting nanoimprinted composite membranes with thin, structurally homogeneous, highly negatively charged polyamide layers demonstrate a water permeance of 53.9 L m-2 h-1 bar-1 with 98.1% Na2SO4 rejection, high Cl-/SO42- selectivity (45), and improved antifouling properties. In active pharmaceutical ingredients enrichment, they achieve one order of magnitude faster methanol transport, e.g., 31.3 L m-2 h-1 bar-1, than commercial membranes. Our nanoimprinted strategy may inspire advanced membrane designs for diverse high-value separations.