Development of nanostructured polyaniline dispersed smart anticorrosive composite coatings

Abstract

Modern engineering science and nanotechnology have hastened the development of high performance corrosion-resistant coatings having a broad spectrum of effectivity under a wider range of hostile environments. The formulation of such coating systems is expected to cause a major revolution in the corrosion world. Conducting polymers have recently proved to be an effective alternative to phosphate-chromate pretreatment that is hazardous due to toxic hexavalent chromium. Moreover, improvements in environmental impact can be achieved by utilizing nanostructured particulates in coating and eliminating the requirement of toxic solvents. The paper reports some preliminary investigations on the corrosion resistance performance of nanostructured methyl orange (MO)-doped polyaniline (PANI)/castor oil polyurethane (COPU) composite coatings on mild steel (MS). The nanostructure of the MO-PANI was confirmed by transmission electron microscopy (TEM). The corrosion protective performance was evaluated by physico-mechanical properties, corrosion rate, and open circuit potential measurements. These coatings were found to act as ''corrosion sensors'' by exhibiting different colors when placed in acid as well as alkaline media. The protective behavior of coatings was attributed to the formation of a passive iron oxide/dopant layer at the metal-coating interface that impedes the penetration of the corrosive ions. Scheme 1. (a) Mechanism of corrosion protection of MO-PANI/COPU coatings. (b) Formation of ferric oxide dopant layer. This figure is available in colour online at www.interscience.wiley.com/journal/pat

Development of sustainable resource‐based nanostructured polyaniline/castor oil polyurethane composites

“…This can be correlated to the dense and opaque nature of PANI. 18 The physicomechanical properties were also found to improve as the loading of MO-PANI increased in the composite. 18 This can be attributed to the increase in the adhesion between conducting materials and metal surface upon increasing the loading of the conductive polymer which enhances the cross-linking between the two components.…”

“…18 This can be attributed to the increase in the adhesion between conducting materials and metal surface upon increasing the loading of the conductive polymer which enhances the cross-linking between the two components. 18 The conductivity of pristine MO-PANI was found to be 2.1 × 10 −3 S/cm while that of 0.5-MO-PANI/COPU, 1.0-MO-PANI/COPU, and 2.0-MO-PANI/COPU was found to be 5.7 × 10 −4 S/cm, 4.3 × 10 −4 S/cm, and 3.5 × 10 −4 S/cm, respectively (Table I). The higher conductivity can be attributed to the homogeneous morphology of the nanocomposites.…”

“…The absorption peak of MO-PANI at 300 nm can be correlated to the π -π * transition in benzenoid ring. 18 The absorption peak around 650 nm can be correlated to the presence of polaronic transitions in PANI. The spectra of MO-PANI resemble that of PANI in conducting state (emeraldine salt form), which confirms the doping of PANI by MO.…”

“…18 The TEM micrographs of 2.0-MO-PANI/COPU composite formed a uniform dispersion of spherical MO-PANI nanoparticles in COPU matrix with particle size in the range of 40-50 nm. 18 Interestingly, no aggregation or cluster formation of the nanoparticles was noticed in the micrograph and the discrete particles of uniform size were found to be dispersed in the COPU matrix. This confirmed the nanostructure of MO-PANI in COPU system.…”

Synthesis of nano polyaniline and poly-o-anisidine and applications in alkyd paint formulation to enhance the corrosion resistivity of mild steel

“…[12][13][14] The design and production of PANIbased coating systems with commercial viability require paint formulations with a minimum possible agglomeration of intrinsic conducting polymer (ICP), well-dispersed nanoparticles (70-100 nm) of uniform size and superior adhesion, 15 as well as the prolonged protective performance under different corrosive conditions. 1,16 The development of conducting polymeric nanoparticles-based corrosion inhibitors with selfcleaning properties, discoloration resistance, and high scratch as well as wear resistance is expected to cause a major revolution in the world of corrosion.…”