Catalytic Effects of Water-Solvated Metal Cations in Epoxy-Amine Curing through Hydrogen Bonds and Metal–Ligand Interactions

Hydrogen bonds and metal-ligand interactions catalyze the epoxy-amine cross-linking reactions. Through a detailed quantum chemical study, it was demonstrated that water, through hydrogen bond formations, acts as a better catalyst than amines in the epoxy-amine cross-linking reactions. The presence of various solvated metal cations (Na⁺, Mg²⁺, and Al³⁺) results in the formation of metal-ligand interactions with both epoxy and amine moieties. A comprehensive investigation of these interactions has been performed in the study to demonstrate that the presence of these cations in small quantities effectively catalyzes the epoxy-amine reactions. The energetic analysis of different metal-epoxy-amine complexes suggests the inhibitory nature of Al³⁺ toward the extent of cross-linking.