BackgroundThe speed of the interfacial polymerization reaction is considered to be the decisive factor for the thickness and surface morphology of the polyamide layer. The reaction rate can be controlled by controlling the diffusion rate of the aqueous monomer.MethodsHere, firstly, polyethylene oxide was added into the aqueous solution to increase the viscosity of the aqueous phase to reduce the reaction rate. Then choline chloride (CC) was grafted on the surface of the nascent polyamide membrane by a surface grafting method for secondary modification. A polyamide nanofiltration membrane with a special Turing structure was prepared on the surface of polyethersulfone support membrane. The desalination performance of composite membrane was investigated.Significant findingsThe results showed that the addition of PEO resulted in the regular Turing structure on the surface of the composite membrane. When the addition amount reached 1%, the performance of the composite membrane was the best. After the secondary modification of CC, the rejection rate of Na2SO4 was more than 96%, and the permeation flux could reach 125.9 L/(m2·h·MPa). It is expected to be applied in the fields of seawater desalination and sewage purification.