In Situ Polymerization of Epoxy Encapsulated Self‐Healing Microspheres: Synthesis, Characterization and Analysis

Microspheres encapsulated with self‐healing agents are smart materials used for advanced technologies like the fabrication of self‐healing composites. Microcapsules filled with dicyclopentadiene (DCPD) are very commonly used in self‐healing composites. However, drawbacks of DCPD, like compatibility with base resin and lower thermal stability, limit its usage in composites. In this study, epoxy resin was encapsulated by urea formaldehyde (UF) as the shell material through a modified in situ polymerization method. The primary advantage of epoxy microcapsules over DCPD microcapsules is their compatibility with the base resin in composites, which is also epoxy. The morphology of the epoxy‐UF microcapsules was studied in SEM. Viscosity of microcapsules at different concentrations in epoxy was measured in a rheometer to identify the optimum quantity of microcapsules in resin (4 wt%). The presence of epoxy functional groups and the thermal stability of epoxy microcapsules were analyzed through FTIR and TGA, respectively. A comparative study was done between epoxy‐UF and DCPD‐UF microcapsules. The major novelties of this work are the improved thermal stability of the epoxy microcapsules (> 200°C) compared to DCPD (70°C) and the compatibility of the healing agent (epoxy) with the base resin of composites (epoxy). The potential applications of these microcapsules as smart materials for making polymer composite structures are discussed.