Composite coating with synergistic effect of biomimetic epoxy thermoset morphology and incorporated superhydrophobic silica for corrosion protection

In this work, potential anticorrosive coating resulted from the composite with synergistic effect of biomimetic epoxy thermoset (BET) morphology and incorporated superhydrophobic silica microspheres was presented. First of all, superhydrophobic methyl-modified silica (MS) microspheres were synthesized by performing the conventional base-catalyzed sol-gel process of MTMS and APTMS. The as-prepared MS microspheres were identified as having an average particle size of ~1 µm in diameter. The as-prepared MS microspheres were characterized by Fourier transform infrared spectrometry (FTIR), 29Si and 13C solid-state nuclear magnetic resonance (NMR) spectroscopy. Morphological properties of MS microspheres and BET-silica composite coating were studied by scanning electron microscopy (SEM). Subsequently, 3 wt% of MS microspheres were incorporated into an epoxy slurry of DGEBA/T-403 in dimetyl acetamide (DMAc), followed by performing the programmed heating through nanocasting technique with PDMS as soft template materials for pattern transfer by using leaf of Xanthosoma Sagittifolium as natural template, leading to the formation of artificial biomimetic composite coating. The appearance/dispersion capability of silica microspheres in BET coating was confirmed by the energy dispersive X-ray spectroscopy (EDX) and Si-mapping. The roughness level of BET and BEC-3% were detected by AFM. The BETsilica composite was found to exhibit a contact angle (CA) of ~153°, revealing the synergistic effect of biomimetic epoxy morphology and incorporated superhydrophobic MS microspheres, which is found to be more hydrophobic than that of neat epoxy thermoset (CA = 81°). Corrosion protection of as-prepared coatings was demonstrated by performing a series of electrochemical measurements (Tafel, Nyquists and Bode plots) upon CRS electrodes in saline condition. It should be noted that the BET coatings upon CRS electrode revealed an effectively enhanced corrosion protection as compared to that coatings without biomimetic morphology. Moreover, the BET coating with superhydrophobic MS microspheres upon CRS electrode was found to exhibit better corrosion protection as compared to a counterpart coating without MS microspheres.