Photothermal self-healing and corrosion resistance of graphene oxide-shape memory epoxy resin/perfluorodecyltrimethoxysilane-polydimethylsiloxane@SiO₂ superhydrophobic coatings

In this paper, based on the two-layer design, a photothermal self-healing superhydrophobic

coating graphene oxide-shape memory epoxy resin (GO-SMEP)/perfluorodecyltrimethoxysilane-polydimethylsiloxane (PFDT-PDMS)@SiO₂ (GO-SMEP/PPS) that could quickly repair physical damages was prepared. Aiming to solve the practical problems of the physical damage repair time is long, the repair rate is low, and stainless steel is susceptible to corrosion under extreme conditions for a long time. The double-layer coating was designed by combination of self-healing coating with photothermal effect GO-SMEP and the superhydrophobic coating with multi-level rough micro-nano structure PPS. Furthermore, the preparation optimization of the coating and its wettability, photothermal effect, corrosion resistance, self-healing and other properties were studied.The results show that when mass ratio of PDMS∶μ-SiO₂∶n-SiO₂=1.5∶1∶1 and the PFDT content is 30wt%, the superhydrophobicity of the GO-SMEP/PPS coating on the 304 stainless steel substrate is the best, and exhibits apparent specularity and high repulsion to droplets. The photothermal effect of the GO-SMEP/PPS coating is enhanced with the increase of the photothermal conversion agent GO content, and the GO-SMEP/PPS coating with a GO content of 0.5wt% is subjected to 3 cycles of near-infrared light cycling radiation, its photothermal effect remains highly stable.The damaged GO-SMEP/PPS coating was placed under 808 nm near-infrared light, and the physical scratches were repaired from 40 μm to about 1 μm after a short period of irradiation for 3 min. Based on the low-frequency impedance modulus of the coating before and after repair (|Z|_{0.01 Hz}) further calculates the restoration rate as high as 97.5%. The AC impedance spectroscopy (EIS) analysis shows that the corrosion resistance of the GO-SMEP/PPS (0.5wt% GO) coating is jointly determined by the GO-SMEP bottom layer and the PPS surface layer, with the largest capacitive arc radius and the low-frequency impedance modulus |Z|_{0.01 Hz} is as high as 3.2×10⁵ Ω·cm², which has the strongest barrier to corrosive media and shows good corrosion resistance. After applying the coating on 304 stainless steel substrate, the measured pitting corrosion potential (E_b=0.263 V) and passive current density (I_p=4.80×10⁻⁸ A/cm²) shows good corrosion resistance to stainless steel.