Design and properties of environmental anticorrosion coating based on m-aminobenzenesulfonic acid/aniline/p-phenylenediamine terpolymer

The waterborne biocompatible alkyd/polyaniline (WARA/PANI) coatings have gained a unique position in anticorrosion coating industry. However, the dispersion and compatibility between WARA and PANI still remain big challenge. Here copolymerization of aniline with aniline derivatives was adopted to prepare PANI, m-aminobenzenesulfonic acid-aniline (SPANI) copolymer, and SPANI copolymer end-capped with p-phenylenediamine (SPANIP terpolymer) aqueous dispersions. The chemical structure of PANI, SPANI and SPANIP was characterized by FT-IR spectra, XRD and UV-vis spectra. PANI displayed spherical particle morphology, while SPANI and SPANIP showed interconnected rod-like structure. The water dispersibility for SPANIP was significantly superior to that of PANI and SPANI, as well as the compatibility between SPANIP and WARA. The as-prepared SPANIP/WARA films also displayed enhanced thermal property and water resistance. The impedance modulus of SPANIP3/WARA coating increased by 4 orders in comparison with WARA coating, and increased by 2 orders compared with PANI/WARA and SPANI/WARA. In comparison with PANI/WARA, E-corr, of SPANIP/WARA shifted from -805 mV to -401 mV, I-corr of SPANIP/WARA decreased by one order, and the corrosion inhibition efficiency increased from 73.8% to 94.3%. SPANIP/WARA coating was also endowed with improved long-term corrosion resistance, and the anticorrosion mechanisms were proposed.