Poly(ionic liquid) membranes (PILMs) can be potentially applied as polyelectrolyte materials in the separation of ampholytes such as amino acids. Therefore, poly(amino acid ionic liquid) membranes (PAAILMs) were prepared by blending poly(amino acid ionic liquids) (PAAILs) and polyvinylidene fluoride (PVDF) in this study. These PAAILMs were characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and thermal gravimetric analysis (TGA). Moreover, their mechanical properties, antibacterial and antifouling properties were evaluated. The zeta potential, pore size distribution, porosity, and specific surface area of these membranes were also measured. The membranes were used to separate the amino acid mixture of L-phenylalanine and L-aspartic acid, which are essential for the synthesis of aspartame. The PAAILMs can be used for the selective separation of L-phenylalanine and L-aspartic acid through the Donnan effect. A maximum selectivity of 65% was obtained for the mixed amino acids via one-step separation. These PAAILMs have the advantages of low operating pressure, high water flux, good antibacterial and antifouling properties, and excellent reusability, thereby indicating their potential for industrial application in the separation of L-phenylalanine and L-aspartic acid. (C) 2020 Elsevier Inc. All rights reserved.