Microbiologically influenced corrosion (MIC) of metals, is the corrosion process assisted by the activity of microorganisms attached to a metal surface. Within metal alloys susceptible to MIC, AA-2024 aluminum, is widely used... [ view full abstract ]
Microbiologically influenced corrosion (MIC) of metals, is the corrosion process assisted by the activity of microorganisms attached to a metal surface. Within metal alloys susceptible to MIC, AA-2024 aluminum, is widely used in the aviation industry for its excellent ratio [mechanical strength / weight]. The most used approach to reduce the damage caused by MIC and electrochemical corrosion comprises a multilayer system. One of the layers, can be obtained by two processes; chromate or chromic acid anodized, in both cases chromium (VI) solutions are used, however environmental regulations have placed restrictions on the use of hexavalent chromium, because of its toxic and carcinogenic characteristics (1). A different approach consists to incorporate agents with biocidal properties to the metal surfaces, or the anti-corrosion coatings. Nevertheless, due to the uncontrolled and continuous release of these agents into the environment, their use could damage the ecosystem. From the foregoing, this work proposes to incorporate SiO2 nanocapsules into the polymeric matrix of an anticorrosive coating of polymethyl (methacrylate), allowing encapsulate biocidal agents in its inner, which will be released if the protective coating is damaged.
The synthesis of SiO2 nanocapsules was performed using a modified Stöber method, using alkoxysilanes as precursor in the presence of ethyl ether and oleic acid, obtaining particles with a narrow size distribution, less than 100 nm, according to measurements of dynamic light scattering (DLS). To incorporate homogeneously the SiO2 nanocapsules into the polymeric matrix, were superficially modified with methyl methacrylate (MMA) by a transesterification reaction. Figure 1 shown X-ray photoelectron spectrum of SiO2 superficially modified with MMA added into a PMMA film, a signal at 286.27 eV corresponds to the Si-OC bond, would indicate that the surface of nanocapsules were modified with MMA, by the joining the hydroxyl groups of nanocontainers, and the carboxyl group of the molecule of MMA, allowing its incorporation into the PMMA matrix.
References
(1) J. H. Osborne, K. Y. Blohowiak, S. R.Taylor, Ch. Hunter, G. Bierwagon, B. Carlson , D. Bernard, M. S. Donley, Testing and evaluation of nonchromated coating systems for aerospace applications, Progress in Organic Coatings, 41, (2001), 217–225.
