Effect of Emulsion Stability on Preparation of Microcapsules by Solvent Evaporation Method

To investigate the preparation technology of the microencapsulated latent curing agent, the curing agent diaminodiphenylmethane-polymethylmethacrylate (DDM-PMMA) microcapsule was prepared by solvent evaporation method with DDM as the core material and PMMA as the wall material. The effects of emulsification methods, surfactants and dispersants on the stability of the emulsion and the forming of the microcapsules were discussed for the preparation of microcapsules by solvent evaporation method. The stability of the emulsion was evaluated by recording the precipitation of the emulsion without stirring. The chemical composition of the surface phase of the microcapsule was characterized by infrared spectra analysis (IR), and the core content was estimated based on the thermogravimetric analysis (TGA) results. The surface morphology of the microcapsule was observed by scanning electron microscopy (SEM). Results show that stable emulsion can be prepared by inversion emulsification with sodium dodecyl sulfate (SDS) and polyamide 650 as the surfactants and polyvinyl alcohol (PVA) as the dispersant. The prepared microcapsule has a spherical appearance, smooth surface, and uniform particle size distribution.