A hydrophilic thin-film-composite (TFC) nanofiltration (NF) membrane has been developed through the interfacial polymerization (IP) of amino-functional polyethylene glycol (PEG) and trimesoyl chloride. The selective layer is formed on a polyethersullone (PES) support that is characterized using FTIR, XPS and SEM, and is dependent on monomer immersion duration, and the concentration of monomers and additives. The higher hydrophilicity alongside the larger pore size of the PEG-based selective layer is the key to a high water flux of 66.0 L m(-2) h(-1) at 5.0 bar. With mean pore radius of 0.42 nm and narrow pore size distribution, the MgSO4 rejections of the PEG based PA TFC NF membranes can reach up to 80.2%. The rejection rates for different salts of the novel membranes are in the order of R(MgCl2) > R(MgSO4) > R(NaCl) > R(Na2SO4); indicating a membrane with positive surface charges. The pore sizes and water permeability of these membranes are tailored by varying the molecular weight and molecular architecture of amino-functional PEG. These newly developed TFC NF membranes show great potential for water softening, wastewater treatment and separation and purification of active, pharmaceutical molecules. (C) 2014 Elsevier B.V. All rights reserved.