Enhancing interfacial properties of epoxy coatings via hyperbranched modification of SiC fillers: Experimental and simulation insights

Abstract

Currently, the issue of inadequate interfacial performance between inorganic fillers and resins in epoxy coatings has garnered significant attention. Therefore, in this study, hyperbranched polymers functionalized with hydroxyl and carboxyl groups were synthesized via a one-step method. The terminal groups of these polymers can undergo dehydration condensation reactions with the silanol groups on the surface of silicon carbide, forming covalent bonds that firmly anchor the polymers to the filler surface. This enhances the interfacial properties between filler and epoxy resin coating. The hyperbranched modified filler coating retains a significantly high impedance modulus following high-temperature and high-pressure corrosion testing. Specifically, the |Z|_0.01Hz value for the EP/HBP-SiC_30% coating reaches 1.15 × 10¹⁰ Ω·cm², which is two orders of magnitude greater than that of the pure epoxy coating. Simultaneously, the simulation results indicate that the EP/HBP-SiC_30% coating has a higher average calculated density, suggesting an improvement in the internal density of the modified coating. Further analysis of the model’s parameters related to the corrosive media reveals reduced diffusion coefficients for CO₂, H₂O, and Cl^-, as well as a decreased free volume fraction. This implies that hyperbranched polymers significantly enhance the dispersion and compatibility of SiC in epoxy resin, thereby effectively improving the barrier performance of the epoxy composite coating against corrosive media. In conclusion, this study offers a theoretical basis for the practical application of hyperbranched modification of inorganic fillers to improve the protective properties of coatings.