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Idalina Vieira Aoki, is Assistant Professor at Polytechnic School - University of São Paulo and head of Electrochemistry and Corrosion Laboratory. She has experience in the field of chemical and materials engineering, working on the following topics: atmospheric corrosion, corrosion inhibitors and treatment of metallic surfaces with polysilanes and hybrid coatings. Currently the focus of her research is on the development of microcapsules containing self-healing agents or inhibitors to be added in paints and also the development of nano-reservoirs obtained by the layer-by-layer method containing corrosion inhibitors. |
Idalina Vieira Aoki
Polytechnic School - University of São Paulo
Abstract
The term functional coatings describes systems that have, in addition to the classical properties of a coating (decorative or corrosion protection), an additional functionality that depends on the actual application of the coated substrate. Another important concept is that of coatings with self-healing properties containing additives as polymeric microcapsules, which have a film former or corrosion inhibitor encapsulated in their core. After a mechanical defect they are disrupted or broken to release the content of their core in the defect site, providing the formation of a polymeric film or allowing the releasing of a corrosion inhibitor to act in the damaged area. The junction of the characteristics and / or functionality of the self-healing coatings give rise to a broader class of coatings so-called smart coatings. This work will present the systems developed for encapsulation of monomers (epoxy ester resin in polyurea-melamine-formaldehyde microcapsules) and corrosion inhibitors (dodecylamine encapsulated in halloysite clay) to be incorporated in epoxy or alkyd coatings, as well as the electrochemical local techniques used in assessing the self-healing effect such as SVET (scanning vibrating electrode technique) and EIS (electrochemical impedance spectroscopy). The self-healing effect was sensed after a reproducible defect was provoked in the coated samples before exposition to the electrolyte. The scanning of the vibrating probe on the defect site can sense the ionic currents formed in the anodic areas moving to the cathodic ones and with a proper calibration in the electrolyte the values of ionic currents can be quantitatively detected. EIS spectra are obtained for different immersion times showing the increase in impedance modulus with time even for samples with a provoked defect.
