Efecto de la incorporación de nanoarcillas exfoliadas sobre las propiedades difusivas de la plata en recubrimientos delgados obtenidos por sol-gel

HUGO GIRALDO MEJÍ; RAÚL A. PROCACCINI; SERGIO PELLICE

Buenos Aires

Conferencia; XIX Congreso Argentino de Fisicoquímica y Química Inorgánica.; 2015

AAIFQ

Due to morphological characteristic of clays, consisting in extremely thin layers of phyllosilicate minerals, they are extensively used as additives controlling the rheological and mechanical properties of paints, cosmetics and in many industrial processes, such as paper making, cement production, and chemical filtering. In the field of sol-gel coatings, phyllosilicates have a strong potential as a controller of diffusive properties of ionic components through the material. A combination of a dip-coating process with well exfoliated clay platelets present in the sol, offers the possibility to obtain coatings with improved barrier and diffusive properties; restricting the diffusion process mainly to the plane direction. In the present study, Laponite, a synthetic smectite clay with a structure and composition closely resembling the natural clay mineral hectorite, was incorporated in hybrid epoxy-silica sol in order to promote a long-term life of silver-ion functionalized hybrid material as antibacterial coating. Sols were synthesized from hydrolytic condensation of tetraethoxysilane (TEOS) and glycidoxypropyl-trimethoxysilane (GPTMS) through acidic catalysis. Silver nitrate was used as a supplier of Ag+ ions. Electrical properties related to silver ion diffusion to the surface were determined on stainless steel AISI 430 by means of EIS. The silver ion diffusion is an important parameter which is, in turn, related to the biocide activity of the coatings. At the same time, the corrosion-potential behaviour was determined on the same samples from polarization curves under the same experimental conditions. Diffusive process was analysed through X-ray fluorescence spectroscopy (XRF). Distribution of clay was studied by grazing incidence X-ray diffraction (GIXRD) and scanning electron microscopy (SEM). Antibacterial properties were analysed by agar diffusion tests with Escherichia coli cultures.