Research Article Smart Mesoporous Silica Nanocapsules as Environmentally Friendly Anticorrosive Pigments C. Zea, 1 R. Barranco-García, 1,2 B. Chico, 1 I. Díaz, 1 M. Morcillo, 1 and D. de la Fuente 1 1 National Centre for Metallurgical Research (CENIM/CSIC), Avenida Gregorio del Amo 8, 28040 Madrid, Spain 2 Institute of Polymer Science and Technology (ICTP/CSIC), C/Juan de la Cierva 3, 28006 Madrid, Spain Correspondence should be addressed to D. de la Fuente; delafuente@cenim.csic.es Received 30 June 2015; Revised 28 August 2015; Accepted 30 August 2015 Academic Editor: Ramazan Solmaz Copyright © 2015 C. Zea et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Nowadays there is a special interest to study and develop new smart anticorrosive pigments in order to increase the protection life time of organic coatings and, simultaneously, to fnd alternatives to conventional toxic and carcinogenic hexavalent chromium compounds. In this respect, the great development of nanotechnologies in recent years has opened up a range of possibilities in the feld of anticorrosive paints through the integration of encapsulated nanoscale containers loaded with active components into coatings. By means of a suitable design of the capsule, the release of the encapsulated corrosion inhibitor can be triggered by diferent external or internal factors (pH change, mechanical damage, etc.) thus preventing spontaneous leakage of the active component and achieving more efcient and economical use of the inhibitor, which is only released upon demand in the afected area. In the present work, the improved anticorrosive behaviour achieved by encapsulated mesoporous silica nanocontainers flled with an environmentally friendly corrosion inhibitor has been evaluated. It has been proven that a change in the pH allows the rupture of the capsules, the release of the inhibitor, and the successful protection of the carbon steel substrate. 1. Introduction Te application of protective organic coatings is one of the most widespread approaches used nowadays for corrosion protection of diferent metallic materials. Te main role of the anticorrosive coating is to protect metals forming efective barrier against corrosive species present in diferent environments. However, the aging of the polymer together with accidental mechanical impacts could lead to the forma- tion of defects interrupting the barrier and providing direct ingress of the corrosive species to the metal surface [1]. Afer corrosion started, the polymer coating itself cannot protect the defective zone and is not able to stop propagation of the defect. For that reason, conventional anticorrosive paint coatings also contain pigments which constantly release sub- stances actively inhibiting corrosion (corrosion inhibitors). However, this continuous and uncontrollable leaching of the active component could lead to fast exhausting and osmotic blistering of polymer flms, both reducing the protection lifetime of the coating. In addition, until recent years, anticorrosive paint for- mulation technologies have relied almost exclusively on the use of chromates as metallic corrosion inhibitor pigments. Diferent types of chromates (Cr 6+ ) have proven to be highly efective pigments in the protection of diferent metals against corrosion, especially in the case of steel. Te great efciency of organic coatings pigmented with chromates is attributed to three factors: (i) suitable solubility of chromate type pig- ments; (ii) high inhibitor efciency; and (iii) establishment of a dynamic process of storage, release, transport, and inhibition [2]. However, the toxicity of these pigments to human health, given their carcinogenic efects [3], and to the environment [4, 5] is giving rise to severe restrictions on their use [6, 7]. All of this has spawned an exhaustive search for envi- ronmentally friendly alternatives to replace this type of anticorrosive pigments and has become the great challenge of the last years for all the sectors involved in anticorrosive protection by organic coatings. When it comes to designing and developing Cr 6+ -free systems, it is necessary to take into Hindawi Publishing Corporation International Journal of Corrosion Volume 2015, Article ID 426397, 8 pages http://dx.doi.org/10.1155/2015/426397