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The monomer concentration is a key factor affecting the diffusion rate and reaction rate of the monomers and determines the physicochemical property of polyamide nanofiltration membranes. However, the mechanism of the monomer concentration effect on the polyamide nanofiltration membrane remains unclear. The properties of nascent membranes fabricated with different monomer concentrations with a fixed ratio presented completely new results in the absence of heat treatment. The results reveal that the polyamide layer thickness increases linearly with the monomer concentration when the concentration is high. The nanofiltration membranes prepared at a low concentration have a larger pore size and a lower cross-linking degree, which contributed to high water permeability. The optimal membrane presented a high pure water permeability of 36.1 L h–1 m–2 bar–1, with the Na2SO4 rejection maintained at 98.4%. This work provides a novel insight into the relationship between the properties of the nanofiltration membrane and monomer concentration.

Superwetting membranes based on steric exclusion and affinity difference have drawn substantial interest for oil/water separation. However, the state-of-the-art membranes fail to literally sort out fouling and permeability decline and so limit their viability for long-term separation. Inspired by Dayu’s philosophy of “draining rather than blocking water”, herein, we achieve a long-lasting and efficient separation for viscous emulsions by designing poly­(hydroxyethyl methylacrylate) (PHEMA)- and polydimethylsiloxane (PDMS)-compensated poly­(vinylidene fluoride) membranes based on coalescence demulsification via chemical coordination phase separation. The symmetric and torturous microporous structure facilitated oil spatial confining and coalescence demulsification, while the synergistic compensation of PHEMA and PDMS coordinated the fouling resist and release properties, which was confirmed by multichannel confocal laser scanning microscopy. The developed membrane shows an unprecedented permeability half-life (τ) for viscous emulsions (e.g., decamethylcyclopentasiloxane, soybean oil paraffin, n-hexadecane, and isooctane) under cross-flow operation, far more beyond common superwetting membranes under applied bench-scale dead-end filtration. Our technique for designing “nonfouling” membranes opens up opportunities for advancing next-generation membranes for oil/water separation.