Effect of Surface Chemistry of Inorganic Materials on Structures and Fracture Behaviours of Epoxy Resin within Nanometres of Adhesive Interfaces

Abstract

Abstract Adhesion and delamination between polymers and inorganic materials are being widely utilized. However, the mechanisms underlying the influence of inorganic material surface chemistry on polymer structures and fracture behaviours near adhesive interfaces are not fully understood; this was studied herein using electron microscopy and molecular dynamics simulations. We prepared adhesive interfaces between epoxy resin and silicon substrates with varying surface chemistries (OH and H terminations) with a smoothness of < 1 nm. The epoxy resins within sub-nanometre distance from the adhesive interfaces exhibited distinct amine-to-epoxy ratios, cross-linked network structures, and adhesion energies. The OH- and H-terminated interfaces exhibited cohesive failure and interfacial delamination, respectively. The substrate surface chemistry impacted the cross-linked structures of the epoxy resins within several nanometres of the interfaces, which resulted in different fracture behaviours and bond strengths. This will help develop durable adhesion with epoxy resins, and potentially help achieve weight reduction in vehicles and other products.