Inhibitor-loaded conducting polymer capsules for active corrosion protection of coating defects

Abstract

This work presents the synthesis of nanostructured hollow polyaniline (PANI) capsules and their application for encapsulation of corrosion inhibitor 2-Mercaptobenzothiazole (MBT). The pHtriggered release of MBT from the capsules was evidenced using UV-vis and Surface Enhanced Raman Spectroscopy (SERS). Incorporation of MBT loaded PANI capsules into epoxy ester coating on AA2024-T3 resulted in a protective system with self-healing ability confirmed by Electrochemical Impedance Spectroscopy (EIS) and Scanning Vibrating Electrode Technique (SVET). The results showed that the incorporation of MBT-loaded PANI capsules into the coating has significantly improved its corrosion protection performance due to the interesting smart characteristics of PANI capsules.

pH-Responsive Nanostructured Polyaniline Capsules for Self-Healing Corrosion Protection: The Influence of Capsule Concentration

“…90 nm. The FTIR and UV-vis spectroscopies [13,16] showed that the capsules have a backbone polymer structure of polyaniline in an emeraldine salt form.…”

“…UV-vis and SERS spectroscopies were used in the previous work [13] to con rm the encapsulation of MBT in PANI containers. In brief, after the encapsulation procedure, the capsules were washed and centrifuged for several times; then, the supernatant of washing of the capsules was studied using UV-vis spectroscopy.…”

“…Although Caps03 and Caps2 coating systems showed poor protection performances with respect to sample Caps1, they still had higher impedance values than those of the control. EIS results for all three coating systems showed three time constants corresponding to capacitance of the coating, oxide layer of bare metal, and corrosion processes in the scratch [13]. EIS spectra were tted using the equivalent circuit presented in Figure 5.…”

“…In our previous work [13], we studied the release of MBT from PANI capsules at di erent pHs (i.e., 1.5, 7, 11). The results from UV-vis and SERS analyses suggested that the encapsulation of MBT corrosion inhibitor in polyaniline hollow microspheres is an e cient way to achieve pH-controlled release of the inhibitor as well as to avoid its undesirable leaching from the coating.…”

“…Their response to chemical or electrical stimuli can make a change in their conductivity, volume, color, permeability, and hydrophilicity [5,[7][8][9][10]. These characteristics make the conducting polymers fascinating candidates to be used as containers for encapsulation and smart release [5,[11][12][13].…”