REDOX-RESPONSIVE RELEASE OF SELF-HEALING AGENT FOR
ANTICORROSION
L.P. Lv 1, Y. Zhao 1, A. Vimalanandan 2, M. Rohwerder 2, K. Landfester,D. Crespy 1
1 Max Planck Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany, E-mail: crespy@mpip-mainz.mpg.de
2 Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Duesseldorf, Germany – e-mail: m.rohwerder@mpie.de
Keywords: capsule, conducting polymer, redox-responsive, self-healing ABSTRACT
The use of self-healing (SH) materials is a promising approach to hinder corrosion. Extrinsic SH materials based on nanocapsules are good candidates because they can be embedded in coatings without impacting negatively on their structures.
Conducting polymers are applied in various fields due to their high electrical conductivity, good thermal and environmental stabilities [1]. Polyaniline (PANI) is one of the most popular conducting polymers. It has three different oxidation states (Figure 1): the fully reduced leucoemeraldine (y=1), the fully oxidized pernigraniline (y=0), and the half-oxidized emeraldine (y=0.5). Therefore, PANI can also exhibit redox-responsive properties upon electro- or chemical stimuli based on which it has been studied for anticorrosion in metal system [2, 3].
In the present study, we proposed a class of self-healing materials structure based on PANI nanocapsules prepared via miniemulsion polymerization and studied their release behavior upon oxidation or reduction. It was found that the PANI capsules exhibited a release of self-healing agent when reduced by reducing agent. This responsive release behavior after reduction may be due to the chemical structure and morphology change which were investigated by fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV-Vis) and scanning electron microscopy (SEM). These conductive nanocontainers are therefore promising for self-healing of corroded metals.
Figure 1: Chemical structure of PANI; the value y dominates the oxidation states. REFERENCES
[1] A.G. MacDiarmid, Synthetic Metals: a novel role for organic polymers, Angewandte Chemie International Edition 40 (2001) 2581-2590.
[2] M. Rohwerder, S. Isik-Uppenkamp, C.A. Amarnath, Application of the Kelvin Probe method for screening the interfacial reactivity of conducting polymer based coatings for corrosion protection, Electrochimica Acta 56 (2011) 1889-1893.
[3] M. Rohwerder, Le Minh Duc, A. Michalik, In situ investigation of corrosion localised at the buried interface between metal and conducting polymer based composite coatings, Electrochimica Acta 54 (2009) 6075-6081.
