Development of an epoxy self-healing coating through the incorporation of acrylic acid-co-acrylamide copolymeric gel

In the current study, a self-healing coating was prepared by the synthesis of an absorbent copolymeric gel on the surfaces of titanium dioxide (TiO2) and its incorporation into epoxy resin. The preparation of the nanogel composite occurred in two steps; firstly, by using 3-(triethoxysilyl) propyl methacrylate (MPS) and then by the absorbent acrylamide (AAm) and acrylic acid (AA) copolymeric gel. The prepared nanogel composite was then added to the epoxy resin in different loading weight percentages (1, 2, and 4). The chemical structure of the synthesized TiO2 nanogel composite was evaluated using Fourier transform infrared (FTIR), and X-ray diffraction (XRD). In order to investigate the thermal stability and morphology of the nanogel composite thermogravimetric analysis (TGA) and Field Emission Scanning Electron Microscopy (FESEM) were utilized, respectively. The result of the characterization tests verified the successful synthesis of the TiO2 nanogel composite. The efficacy of the incorporation of the TiO2 nanogel composite on the self-healing behavior of the epoxy coatings was assessed in 3.5 wt.% NaCl solution by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The prepared nanogel composite exhibited excellent barrier properties against corrosive media. Functionalized TiO2 nanoparticles were found to noticeably enhance the anticorrosive behavior of the epoxy coating. Furthermore, the results verified the epoxy resin containing 1 wt.% of TiO2 nanogel composite as the most anticorrosive sample with the healing efficiencies of 98 % and 94 % obtained from the EIS and potentiodynamic polarization tests, respectively.