Preparation and Molecular Dynamics Simulation of Encapsulated Modified Imidazole as an Accelerator of Single-Pack Epoxy Adhesive

This study presents the synthesis and molecular dynamics (MD) of an encapsulated modified imidazole (EPMIM) accelerator for single-pack epoxy-anhydride adhesives. EPMIM was synthesized through a facile two-step, one-pot reaction of epoxy resin and phenyl glycidyl ether (PGE)-modified imidazole. Structural characterization by NMR, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and gel permeation chromatography (GPC) confirmed the successful encapsulation of the active sites, which remained stable at room temperature. Upon heating, the hydrogen bonds and π–π conjugation within the structure are disrupted, triggering its catalytic function and promoting the rapid curing of the epoxy-anhydride system. Molecular dynamics simulations were utilized to analyze the self-assembly processes and thermodynamically stable configurations of EPMIM, demonstrating that the self-assembly is primarily driven by intermolecular hydrogen bonds and electrostatic interactions. The catalytic performance of EPMIM in the single-pack epoxy-anhydride formulation was evaluated by determining the glass transition temperature (Tg) of the cured resin, with an optimal EPMIM addition of 5% being established. Further thermodynamic and storage stability analyses confirmed that EPMIM provides excellent long-term stability and high reactivity as a latent curing accelerator.