All-in-one in-situ constructed neutral inhibitors entrapped polyaniline fibers enable robust anti-corrosion polymer coatings

Abstract

Polyaniline (PANI) is widely employed as a filler to boost the corrosion resistance of organic coatings, leveraging its notable passivation ability and redox properties. However, its efficacy in protecting against corrosion is mainly confined to small defects such as pinholes due to the specific redox characteristics of PANI and the counterions it releases, which restricts further improvements in anticorrosive performance. To extend the repair capability of PANI fibers to large damaged areas, we propose entrapping neutral corrosion inhibitors within the PANI fibers. This was achieved by preparing benzotriazole (BTA)-entrapped HCl or sulfosalicylic acid (SSA)-doped PANI fibers through a one-step chemical oxidative polymerization process. The effects of various counterions and neutral inhibitors on corrosion protection were explored. A comprehensive release experiment examined unwashed and washed BTA-entrapped HCl or SSA-doped PANI fibers, confirming their pH-responsive controlled release capabilities. The results indicated that incorporating these fibers into polyvinyl butyral (PVB) coatings significantly enhances anti-corrosive performance compared to coatings without entrapped neutral corrosion inhibitors. Specifically, the low frequency impedance magnitude for PANI-SSA-BTA/PVB and PANI-HCl-BTA/PVB coatings increased by sixfold and elevenfold, respectively, over the pure PVB coating. This enhanced performance is attributed to the synergistic effect of the passivation of PANI fibers and the controlled release of BTA. The development of neutral corrosion inhibitors entrapped within acid-doped PANI represents an innovative approach to creating high-performance anticorrosion coatings, holding significant potential for advancing applications in corrosion protection.