The preparation of nanocomposites having antibacterial activity, composed from Polyolefins matrix with dispersed metallic silver nanoparticles (AgNPs), and no containing other chemicals then the polyolefin and the silver AgNPs, is per- formed according to an inventive one pot very sustainable procedure starting from a porous and porous covalently functionalized semicrystalline polymer powder suspended in distilled water and AgNPs water suspension, which was produced in situ, by chemical or physical methods or also manufactured separately and added in a short time. The prompt fixation for absorption into the pores and also to polar interactions at the interface, of the metal particles on the polymer maintains their nanometric size without the need of other stabilizing chemical products, as in other cases. The leaching of silver nanoparticles to the environment is hindered by the porosity of the adsorbing support and eventually by the silver binding groups covalently connected to polyolefins. The AgNPs remain then available for the antibacterial activity due to the absence of stabilizers that would act as barriers towards contact Silver-bacteria. These nanocomposites, as such or in mixture with polymer not containing AgNPs can be subjected to melting molding processes by conventional methods maintaining the antibacterial activity. Therefore, the materials thus produced constitute a highly sustainable raw material for the production of plastic products of various types with antibacterial activity.Selon la présente invention, la préparation de nanocomposites ayant une activité antibactérienne composés dune matrice de polyoléfines avec des nanoparticules dargent (AgNP) métalliques dispersées, et ne contenant pas dautres produits chimiques que la polyoléfine et les AgNP dargent, est réalisée selon une procédure monotope très durable selon linvention à partir dune poudre de polymère semi-cristalline poreuse et poreuse fonctionnalisée de manière covalente en suspension dans
