Design on the corrosion protection of eco-friendly and multifunctional polyhedral oligomeric silsesquioxane functionalized graphene oxide reinforced waterborne polyurethane

This paper explored that the novel waterborne polyurethane (WPU) composite coatings with superior corrosion protection performance was fabricated via intercalating functionalized graphene oxide (GO). The eco-friendly and superhydrophobic aminoethyl aminopropyl isobutyl polyhedral oligomeric silsesquioxane (POSS-NH-NH₂) was applied to modify GO via facile one-step chemical grafting. Several analyses such as FT-IR, XRD, Raman, and SEM were performed to verify the successful graft of POSS-NH-NH₂ into the GO. Sequentially, the WPU and WPU composite coatings containing GO and functional graphene oxide (PNNG) nanoparticles were prepared and applied on Q235 steel with a thickness of 55 ± 5 µm. The corrosion protection performance of coatings was investigated by electrochemical impedance spectroscopy and potentiodynamic polarization. The results highlighted that well-dispersed and hydrophobic PNNG nanoparticle remarkably enhanced the corrosion protection performance of WPU. In detail, the protection efficiency of WPU composite coatings with 0.1 wt% PNNG reached 99.79% relative to pure WPU. After 21 days’ immersions in 3.5 wt% NaCl aqueous solution, the ǀZ|_{f = 0.01 Hz} of WPU decreased to 1.96 × 10⁵ Ω cm² from 1.52 × 10⁷ Ω cm². However, the ǀZ|_{f = 0.01 Hz} of WPU with 0.1 wt% PNNG was 1.48 × 10⁸ Ω cm² after 180 days’ immersions, which was still about 3 orders of magnitude higher than that of WPU.