Synthesis and characterization of silver-rich coatings loaded with functionalized clay nanoparticles

• Published in: Journal of sol-gel science and technology 2018-03, Vol.85 (3), p.529-538
• Main Authors: Giraldo Mejía, Hugo Fernando, Procaccini, Raúl Ariel, Pellice, Sergio Antonio
• Format: Article
• Language: English
• Subjects: Austenitic stainless steels; Ceramics; Chemical synthesis; Chemistry and Materials Science; Composites; Condensates; Diffusion rate; Dip coatings; Electrochemical analysis; Glass; Immersion coating; Inorganic Chemistry; Leaching; Materials Science; Nanoparticles; Nanotechnology; Natural Materials; Optical and Electronic Materials; Original Paper: Functional coatings; Protective coatings; Silicon dioxide; Silver; Sol-gel processes; Sols; Structural analysis; Submerging; Substrates; Tetraethyl orthosilicate; thin films and membranes (including deposition techniques)
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-018-4600-7

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.