Novel silver/polyurethane nanocomposite by in situ reduction:: Effects of the silver nanoparticles on phase and viscoelastic behavior

A novel silver/poly(carbonate urethane) nanocomposite was prepared through in situ reduction of a silver salt (AgNO3) added to a solution consisting of a commercial poly(carbonate urethane) dissolved in NN-dimethylformamide (DMF). In this system, the presence of the poly(carbonate urethane) was proved to protect the silver nanoparticles, whose formation was confirmed by means of UV-vis spectroscopy, from aggregation phenomena. The silver morphology developed in the solid state after DMF casting was imaged by FESEM. Homogeneous dispersion of silver nanoprisms in the poly(carbonate urethane) matrix was clearly observed. The effects of dispersion of silver nanoparticles within the poly(carbonate urethane) matrix were investigated by means of ATR-FTIR and multifrequency dynamic mechanical thermal analyses. The obtained results revealed that the presence of silver nanoparticles modifies both the phase and the viscoelastic behaviors of poly(carbonate urethane). As a matter of fact, the hydrogen bond formation in the hard and soft segments was found to be hindered and the molecular motions of the soft segments were restricted, because a comparatively higher activation energy was required for the related a-relaxation process. (c) 2008 Wiley Periodicals, Inc.