Organic-inorganic hybrid epoxy resin coating with high thermal stability and hydrophobicity for corrosion protection prepared by (3-aminopropyl) triethoxysilane as a bridging agent

The corrosion protection application of epoxy resin (EP) in high-temperature environments is greatly restricted due to thermal stability limit and inherent hydrophilicity. In this study, a hybrid epoxy resin was synthesized by grafting hexadecyltrimethoxysilane (HDTMS), 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (PFDTMS), and tetraethyl orthosilicate (TEOS) onto the molecule of epoxy resin, using (3-aminopropyl) triethoxysilane (APTES) as a bridging agent. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses revealed the presence of C-N bonds and Si-O-Si bonds in the hybrid epoxy resin, confirming the success of the hybridization. Compared to pure epoxy resin, the hybrid epoxy resin coating effectively enhances the thermal stability while maintaining both corrosion resistance and hydrophobicity. Thermal gravimetric analysis (TGA) indicated that the initial decomposition temperature (T5%) of the hybrid epoxy resin coating increased from 327°C to 372°C. This enhancement is attributed to the introduction of Si-O-Si bonds and an increase in cross-linking density in the hybrid epoxy resin. Water contact angle measurements showed that with the introduction of C-F bonds and long carbon chains, the contact angle increased from 71° to 106°. The hydrophobic hybrid epoxy resin coating maintained a contact angle of 100° at 300°C for 300 hours. The transition from hydrophilicity to hydrophobicity improves the corrosion resistance of the coating.