Smart acrylic coatings for corrosion detection

Corrosion detecting coating was prepared using acrylic polymer chemically modified with 5-acrylamido-1,10-phenanthroline (AMP). Modified polymers having varied AMP content were synthesized and characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetric (DSC) and thermo gravimetric (TGA) analysis. The modified polymer after complex formation with Fe2+ ions showed additional absorption peak at 359 nm in UV-vis spectrum confirming the polymer-Fe (II) complex formation. Corrosion sensing ability of these polymers was evaluated by immersing the coated mild steel panels in 3.5% NaCl solution and visually monitoring the color change of coating. Electrochemical impedance spectroscopy (EIS) was used to measure the polarization resistance (RPR) of coated steel specimens and correlated with the color change of coating. Coating from the point of color change was removed and bare metal was analyzed by scanning electron microscopy (SEM) to reconfirm that the point of color change was the corrosion site. Results reveal that these new sets of polymers can be used for corrosion detection.