In situ polymerization of (4-vinylbenzyl)-N-methyl-D-glucamine (VbNMDG) for the formation of thin-film composite membranes with boron retention capacity is reported.VbNMDG was synthesized from vinylbenzyl chloride and N-methyl-D-glucamine, afterward, a mixture constituted by VbNMDG, a radical initiator and a crosslinking reagent was injected and polymerized in the inside of the pores of the membranes.Functionalization of vinyl monomer was verified by nuclear magnetic resonance.Analyses of scanning electron microscopy (SEM), diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and contact angle measures were performed to unmodified and modified membrane surface.Changes on the surface porosity and permeability were evaluated from Hagen-Poiseuille model.In addition, boron retention capacity was evaluated by diafiltration experiments.Results suggest that active layer was modified as a result of polymerization reaction; in consequence, the pore diameter and hydraulic permeability were significantly decreased. Thin-film compositeUltrafiltration membrane N-methyl-D-glucamine Interpenetrating polymer network Compositos de películas delgadas Membranas de ultrafiltración N-metil-D-glucamina Redes poliméricas interpenetrantes