Publication: Graphene/polyaniline conductive polymer nanocomposite coatings by in-situ interfacial polymerization for corrosion protection of steel
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Date
2024-12-01
Authors
Muhammad Firdaus, Shafee
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Abstract
Mild steel is one of the most used metals for various infrastructure applications. However, the corrosion of mild steel components in a harsh environment restricts their practical usability. Protective coatings are increasingly used to limit the penetration of corrosive species. Conductive polymer (CP), such as polyaniline (PANI) are identified as active materials in protective coatings. The main aim of the study is to develop graphene (Gr)/PANI nanocomposite coatings for corrosion protection of mild steel. However, the main challenge in developing effective anticorrosion coatings using CP nanocomposites is to achieve optimal electrical and thermal conductivity while ensuring proper dispersion of NP fillers. Comparison of the fabrication methods (in situ interfacial polymerization and solvent blending) and the effect of dodecylbenzene sulfonic acid (DBSA) surfactant on the properties of Gr/PANI nanocomposites are explored in the study. The effect of different Gr/PANI filler loadings and types of nanoparticle (NP) fillers (Gr, synthetic diamond (SD) and multi-walled carbon nanotubes (MWCNTs)) filled PANI and oil paint on the corrosion protection of mild steel was also considered in the study. Gr/PANI nanocomposites produced by the in situ interfacial polymerization method showed 545 % improvement in electrical conductivity, 20 % in thermal conductivity and thermally stable than the solvent blending method. The in-situ interfacial polymerization method exhibits a smaller diameter size of PANI fiber and good Gr filler dispersion in PANI. The addition of
DBSA created a homogeneous dispersion of Gr filler within the PANI matrix and improved its properties. Gr/PANI nanocomposites with the addition of 5 wt.% fillers (5 Gr/PANI) with paint showed great anticorrosion results for potentiodynamic polarization, electrochemical impedance spectroscopy, immersion and contact angle, if compared to other samples. Results show that 5 Gr/PANI nanosheets have formed a stacking physical protective layer and prevented the penetration of the corrosive species by creating the tortuosity of the diffusion pathway. However, the addition of high filler loadings has reduced the scratch-resistant properties since the NP fillers altered the adhesiveness and reduced the paint protective action. In conclusion, 5 Gr/PANI nanocomposites with paint have successfully improved the anticorrosion properties of the paint and lowered the corrosion rate of the mild steel sample.