Enhancement of barrier and corrosion protection properties of epoxy coatings by aminofunctionalized silica nanoparticles in epoxidized eucommia ulmoides gum/epoxy double crosslinked networks

Abstract

In this study, we prepared an epoxy resin-based coating characterized by a double crosslinked network, which exhibits superior mechanical and anti-corrosion properties. The nano-silica surface, modified by N-(2-aminoethyl)-3-aminopropyl trimethoxysilane (KH792), features an abundance of reactive groups. These groups interact with the reactive groups on the molecular chain segments of the adjacent coating matrix. Simultaneously, the epoxy groups in the epoxidized eucommia ulmoides gum (EEUG) are able to react with the curing agent, contributing to the formation of a denser three-dimensional crosslinked network within the coating. This interaction improves the coating’s mechanical properties, adhesion, and corrosion resistance. Furthermore, the nano-silica forms bonds with the hydroxyl groups on the metal substrate surface, improving the coating’s adhesion by increasing the number of bonding sites. The EP/EEUG coating, containing 5 wt% KH792-SiO₂, demonstrates the highest Shore hardness and exhibits exceptional adhesion strength of 11.09 MPa, which represents a 54.2% increase compared to the composite coating without nano-silica. This addition also leads to a higher crosslinking density, significantly improving the corrosion protection and tensile strength of the composite film. At a nano-silica concentration of 5 wt%, the composite coating shows the largest arc tolerance radius and the highest coating resistance, with an impedance value of 9.86 × 10⁹ Ω cm² after a 15-day immersion in a 3.5 wt% NaCl solution.

Graphical abstract