Caracterización electroquímica fisicoquímica de un nanomaterial híbrido Nafion/Ag-NPs

La particular estructura quimica de la matriz perfluorosulfonica del Nafion, con dominios hidrofilicos e hidrofobicos segregados formando canales nanoscopicos, ha dado pie a su uso como modelo de estructura para la fabricacion de nanocompuestos polimero-metal mediante el crecimiento de nanoparticulas metalicas en su interior. En particular, mediante la tecnica de sintesis intermatrical se ha conseguido el crecimiento de nanoparticulas de plata (de un tamano medio proximo a los 10 nm), las cuales presentan una distribucion particular en forma de lineas casi paralelas, que difiere de la distribucion mas habitual de mayor concentracion en la superficie. Para evaluar posibles aplicaciones de este nuevo material se ha realizado su caracterizacion mediante diferentes tecnicas: microscop1ca, analisis quimico superficial, mecanica, electrica/electroquimica. Los resultados obtenidos muestran que la presencia de nanoparticulas no parece afectar significativamente al transporte de protones en la membrana, pero si modifican la superficie de la misma. Ademas, la resistencia mecanica del nuevo material es inferior a la del Nafion no modificado debido a la interaccion de las particulas con las cadenas de polimero. Tambien se ha observado que algunas de estas propiedades varian de forma importante en/uncion del grado de hidratacion de la muestra. The particular chemical structure of Nafion, a perfluorosulfonic matrix with segregated hydrophilic and hydrophobic domains forming nanoscale channels, has led to its use as a model structure for the manufacture of polymer-metal nanocomposites by growing in it metal nanoparticles. in particular, using the technique of intermatrix synthesis, the growth of silver nanoparticles (with an average diameter close to 10 nm) has been achieved Moreover, samples exhibit a particular distribution of such nanoparticles in the form of nearly para/le/ fines, what differs from the usual major distribution on the membrane surface. To evaluate the potential application of this new material in electrochemical applications, we proceeded to their characterization by different techniques: microscopic, surface chemical analysis, mechanical and electrical/electrochemical. These results show that the presence of nanoparticles does not seem to significantly affect the transport of protons in the membrane bulk, but it modifies its surface. Furthermore, the mechanical strength of the new material is lower than the unmodified Nafion due to the high interaction between nanoparticles and polymer chains. Moreover, it was a/so observed that some of the mentioned properties significantly varied depending on the degree of hydration of the sample