Synthesis and characterization of silver-rich coatings loaded with functionalized clay nanoparticles
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A synthetic exfoliated nanoclay smectite type, Laponite® S482, was incorporated as a functionalized load in a silica hybrid matrix synthesized by the sol–gel route. The previous functionalization was carried out through a “grafting” reaction with (3-glycidoxypropyl)trimethoxysilane (GPTMS) assisted by ultrasonic dispersion. The precursor sols were synthesized by acid-catalyzed hydrolytic condensation between tetraethoxysilane (TEOS) and functionalized GPTMS, a silver ions source was added in order to obtain a coating material with controlled silver releasing properties. Coatings were obtained by “dip-coating” on different substrates. Structural characterization of the coatings was conducted by SAXS and SEM-EDS, the results revealed a complex silica matrix with intercalated nanoclays, an organic fraction and a homogeneous content of Ag+. The electrochemical characterization was realized by EIS tests on stainless steel coated substrates AISI 316L type; the results showed good barriers properties and a high integrity of the coatings loaded with nanoclay. The evolution of the release of Ag+ ions was studied by XRF, through exposing the coatings to a leaching process at steady state and determining the residual content of Ag within the coat at different immersion times. It was found that the addition of 1.5 wt. % of clay, in respect to condensed silica, decreased the initial diffusion rate of Ag+ ions at near the half part, allowing its potential use in the development of antibacterial coatings with longer terms of life.
KeywordsSol–gel Nanoclays Silver ions Hybrid coating Silver release
Authors want to acknowledge the Argentine National Council of Scientific and Technical Researches (CONICET, PIP 2012-0434) and the National Synchrotron Light Laboratory of Brazil (LNLS, Project 6780/10, proposal D11A-SAXS1-15291) for the financial supports. In addition, Mr. Martín E. Lere is gratefully acknowledged for his helpful technical collaboration.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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