The encapsulation of 1-methylimidazole (1-MI) curing agent was investigated to prepare the latent curing agent by using solid epoxy resin as the wall materials. The morphology of 1-MI/solid epoxy microcapsules was investigated by optical microscopy and scanning electron microscopy (SEM). The thermal behavior of the prepared microcapsule was investigated using differential scanning calorimeter (DSC) and thermal gravimetry analysis (TGA). According to the hot‐stage optical microscopy at 120 oC, by heating the microcapsule in liquid epoxy resin, although the solid epoxy shell was in contact with core 1-methylimidazole curing agent for a long time (about two years), the microcapsule shell melts. These optical microscopy images show that all the epoxy functional groups of the microcapsule’s shell were not consumed and solid epoxy shell is thermoplastic.
