Method for providing a substrate with an antimicrobial coating, and coated substrates obtainable thereby

The invention relates to the field of antimicrobial materials, in particular to implantable and other medical devices exhibiting antimicrobial activity. Provided is a method for providing a substrate with an antimicrobial coating by immobilizing a quaternary ammonium compound onto the surface of said substrate, comprising the polycondensation of AB2 monomers comprising a secondary amine as A-group and blocked isocyanates as B-groups to obtain a low number average molecular weight polyurea of at least 2500 Da, contacting said polyurea with a surface grafted with coupling agent to covalently anchor the polyurea, and continuing polycondensation to obtain a hyperbranched polyurea coating; followed by immobilizing onto said coating a hydrophobic N-alkylated polyethylenimine (PEI) having antimicrobial properties.