CONICET | Buscador de Institutos y Recursos Humanos

The incorporation of inorganic nanoparticles such as silver NPS into polymers has proved to be an effective method to improve the performance of different polymer materials. Here, we report a simple and efficient procedure for the in-situ preparation of methacrylate monomer (2,2-bis[4-(2-methacryloxy ethoxy)phenyl]propane)/Ag nanocomposites. Silver nanoparticles were generated by in situ reduction of silver ions using 4-Methoxyphenol (MEHQ) as reducing agent. Silver nitrate solutions (AgNO3) of different concentrations in absolute alcohol were prepared and incorporated into methacrylate resin at room temperature. After mixing, these samples were heated under darkness at 80 ºC for 24 h. This time was enough to ensure complete reduction of silver ions, and to evaporate all the alcohol. At this time, the color of the solution gradually changed from colorless to golden yellow and then to pale brown dependent on the concentration Ag NPs. The resins containing different amounts of silver NPs homogenously dispersed were stable over time. They were activated for UV-light polymerization by the addition of 2,2-dimethoxy-2-phenylacetophenone (DMPA). The UV light source was assembled from light emitting diodes (LED) with irradiance equal to 260 mW/cm2 centered at 365 nm (OTLH-0480-UV, Optotech). The resulting nanocomposites were characterized by X-ray diffraction and UV-Vis spectroscopy. The results of UV-Vis spectroscopy indicated the presence of UV-vis absorption peaks between 418-434 nm. The conversion of methacrylate groups was measured by Fourier-transformed near-infrared spectroscopy. The conversion profiles, calculated from the decay of the absorption band located at 6165 cm−1, showed that the initial velocity of the reaction decreased as the Ag NPs concentration increased. However, the value of conversion after 160 seconds of irradiation was the same for all the resins studied.