Progress in Organic Coatings 95 (2016) 127–135 Contents lists available at ScienceDirect Progress in Organic Coatings j o ur na l ho me pa ge: www.elsevier.com/locate/porgcoat Steel protection of two composite coatings: Polythiophene with ash or MCM-41 particles containing iron(III) nitrate as inhibitor in chloride media José Luis Gutiérrez-Díaz a , Jorge Uruchurtu-Chavarín a,∗ , Marisol Güizado-Rodríguez a,∗ , Victor Barba b a Centro de Investigación en Ingeniería y Ciencias Aplicadas (CIICAp-IICBA), Universidad Autónoma del Estado de Morelos (UAEM), Av. Universidad No. 1001, Col. Chamilpa, C.P. 62209 Cuernavaca, Morelos, Mexico b Centro de Investigaciones Químicas (CIQ-IICBA), Universidad Autónoma del Estado de Morelos (UAEM), Av. Universidad No. 1001, Col. Chamilpa, C.P. 62209 Cuernavaca, Morelos, Mexico a r t i c l e i n f o Article history: Received 18 September 2015 Received in revised form 17 February 2016 Accepted 3 March 2016 Available online 25 March 2016 Keywords: Composite corrosion coatings Polythiophene derivative Electrochemical noise analysis Fast Fourier transform a b s t r a c t This work presents the evaluation of two corrosion protection coatings applied to mild steel which was exposed to a 3% chloride solution at different immersion times. The coatings were processed compos- ites (P1 polymer-ashes and P1 polymer-MCM-41) using iron (III) nitrate as a corrosion inhibitor in their matrix. P1 polymer is a polythiophene derivative of 3-HT and (S)-(-)-1-(4-nitrophenyl)pyrrolidin-2- yl)methyl-2-(thiophen-3-yl)acetate. Ashes and MCM-41 (a type of mesoporous silica material) were used as containers of the iron (III) nitrate inhibitor. The coatings were characterized using nuclear magnetic resonance (NMR), Fourier Transform Infrared (FT-IR) and scanning electron microscopy (SEM). Polariza- tion curves were used to determine the optimal concentration of inhibitor, and electrochemical noise measurements (ENM) to evaluate the corrosion protection performance. The electrochemical noise anal- ysis (ENA) included: statistical (standard deviation) and Fast Fourier Transform (FFT) analysis to obtain the impedance spectrum and to evaluate the corrosion coating system’s behavior. Good performance was obtained with the two anti-corrosion coatings that were applied and their inhibitor containers. © 2016 Elsevier B.V. All rights reserved. 1. Introduction While traditional coatings are designed to protect the metal sub- strates to which they are applied by providing a barrier between the surface and the environment, compelling innovations have been made with regard to “smart” coatings [1]. These novel coatings are far superior to the traditional ones in that they release corrosion inhibitors as required by the presence of damaged coating in corro- sive environments. Recent work has focused on the self-contained corrosion control or “self-healing” potential of smart coatings [2,3], resulting in a new-generation of effective anti-corrosive systems. The new coatings possess nanocontainer functionality: an active passive matrix that responds to changes in the local environment. The main objective today is to employ nano-mesoporous struc- ∗ Corresponding authors. E-mail addresses: juch25@uaem.mx (J. Uruchurtu-Chavarín), marisolguizado@uaem.mx (M. Güizado-Rodríguez). tured materials dispersed in the polymer matrix of the coatings as corrosion inhibitor storage containers [1–3,21–25]. The study of the protection of metals and alloys from corrosion, using organic coatings, has been a research area of great interest leading to novel anti-corrosion paints and polymers [4–7]. Specif- ically, conducting polymers (CPs) are now starting to be used as organic coatings, where these form dense, adherent films with low porosity that restrict the entry of oxidizing agents and thus reduce metal corrosion [5,6]. These coatings provide corrosion resistance in saline and acid environments, with the added benefits of flex- ibility, insolubility and adhesion to the substrate [6,7]. Metals are severely damaged by localized corrosion in different environments, especially those containing chloride ions [8,9]. CPs form a passive film, a very thin metal oxide layer (iron oxide in the case of steel) which condenses on the metal surface, reducing naturally and to a great extent the corrosion rate of chloride ions. However, these films are not uniform, and the corrosion process of localized oxide breakdown persists through their fissures, resulting in a fast disso- lution of metal [10,13]. The combined use of coatings and inhibitors dispersed in a polymer matrix has proved to be useful when deal- http://dx.doi.org/10.1016/j.porgcoat.2016.03.005 0300-9440/© 2016 Elsevier B.V. All rights reserved.