Inspired by mussel adhesive proteins, catechol functional groups play an important role in the ability of the mussel to adhere to organic and inorganic surfaces. A novel functional polyurethane (PU) based on hydrolysable tannins that contain a number of catechol groups was successfully synthesized and characterized. These catechol groups were used as a reducer for Ag (I) to form Ag (0), and to prepare polyurethane/silver nanoparticles composites. These kinds of polyurethane containing Ag nanoparticles showed obvious inhibition of bacterial growth because of the conjunct actions of the well-known antibacterial property of silver and the antifouling property of PEG. It is possible for these materials to be applied widely into antibacterial adhesive coatings for surface modification due to their low cost and the material-independent adhesive property of catechol groups in tannins. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41349.