Water‐Mediated Epoxy/Surface Adhesion: Understanding the Interphase Region

Abstract

Epoxy resins coatings are commonly found in corrosion protection coatings but the presence of water can affect their adhesion to the substrate, often weakening the adhesion of the coating to the solid, reducing its efficiency. Nevertheless, small amounts of water can enhance the epoxy/ substrate interactions. In this work, the interphase region of an epoxy precursor and metal oxide substrates is investigated using molecular simulations and it is found that water accumulates between the epoxy layer and the solid substrate.At high water concentrations (9 wt %) the interaction between the epoxy precursor and the solid surface is weakened regardless of the nature of the solid, but at low water concentrations the nature of the solid surface becomes important. For hematite, the presence of water decreases the strength of adhesion but for goethite the presence of a small amount of water (3 wt %) enhances the adhesion to the surface resulting in a densification at the interface.

Influence of Water on an Epoxy/Amine–Metal Interphase: A Combined DFT and Mixing Calorimetry Approach

“…To go further, reactive force fields have been developed to reproduce the creation of bonds between the solid and the amine and prove the implication of N in interaction with the metal site . Recent studies have illustrated the complex role of water in the interphase which, can enhance the interaction between epoxy and metal surfaces and analyze the opposite behavior of the systems in the presence of goethite or hematite …”

“…25 Recent studies have illustrated the complex role of water in the interphase which, can enhance the interaction between epoxy and metal surfaces and analyze the opposite behavior of the systems in the presence of goethite or hematite. 26 Water molecules could play the role of fourth reactant in epoxy/amine−metal systems but have not yet received dedicated attention. This is the objective of the present contribution, with the aim of exploring the impact of water in the DGEBA−DETA−Al system, by a dual approach combining experiments (in situ mixing calorimetry and DSC) and DFT calculations.…”

Segregation in epoxy/amine systems on iron oxide surfaces

“…Fig.8An overlay of Fig.7cwith a render of the adsorption of water oxygen atom adsorption sites (grey circles) at the same goethite surface, from previous work 47. Surface regions devoid of monomer atoms that could contain a number of water molecules are circled in black.…”