Polyaniline/polyacrylate core–shell composites: Preparation, morphology and anticorrosive properties

•Successfully prepared nanoparticles via emulsifier-free emulsion polymerization.•Polyaniline/polyacrylate core–shell composite was prepared.•Proposed strawberry-like morphology of nanocomposite.•Anticorrosive properties improvement of nanocomposite coated steel.•Lowest corrosion rate of nanocomposite coated steel was 1.168 mm/year.

Polyaniline/partially phosphorylated poly(vinyl alcohol)/polyacrylate nanoparticles ((PAn/P-PVA)x/PAcy) were synthesized by encapsulation of varying amounts of PAn/P-PVA nanoparticles (x = 0.3, 0.5 or 0.7 g) with PAc (y = 4, 6 or 8 g acrylate monomers) via emulsifier-free emulsion polymerization. A monomer conversion level of 93.9% was achieved for the synthesis of the (PAn/P-PVA)0.5/PAc4 nanoparticles. X-ray diffraction analysis revealed that PAc was intercalated between the PAn/P-PVA layers, whilst transmission electron microscopy analysis of the different nanoparticles revealed they were spherical PAn/P-PVA agglomerates coated with PAc. Thermogravimetric analysis revealed that the thermal stability of the (PAn/P-PVA)/PAc nanoparticles decreased with increasing amounts of PAc. Cyclic voltammetry based analysis of the different (PAn/P-PVA)/PAc nanoparticles coated onto carbon fiber electrodes revealed that the PAn/P-PVA nanoparticles were encapsulated sufficiently by the non-conductive PAc and that the peak current decreased with increasing amounts of acrylate. With respect to the corrosion resistance in 1.0 M sulfuric acid, steel coated with the (PAn/P-PVA)0.7/PAc8 nanocomposite showed the best corrosion resistance (11.4%), but for the nanocomposites at each PAn/P-PVA loading level, the anticorrosive properties increased with increasing PAc levels, presumably due to the increasing tortuosity of the diffusion pathway through the coating for any corrosion agents.

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