Interfacial polymerization of an epoxy resin and carboxylic acids for the synthesis of microcapsules

BACKGROUND: Microencapsulation technology promises new applications such as intelligent microstructures, phase change materials and self-healing composites. Microcapsule synthesis and characterization have been researched extensively; however, the well-known polymerization between epoxy resins and carboxylic acids has not been used to prepare microcapsules. RESULTS: Microcapsules were prepared by interfacial polymerization of an oil-in-water emulsion which contained a commercial epoxy resin and multifunctional carboxylic acids. The microcapsules obtained were characterized using optical microscopy and scanning electron microscopy. Experiments performed at lower stirring rates led to larger microcapsules, in the range 100-400 gm, while higher stirring rates resulted in microcapsules in the range 10-50gm. CONCLUSIONS: Microcapsules can be prepared by interfacial polymerization of epoxy resins, an extensively studied and widely used class of polymers. By means of NMR characterization we gained insight into the mechanism of polymerization at the interface wherein products coming from the more hindered ring opening as well as from intermolecular transesterification are identified. The presence of a crosslinker affects the morphology of the external microcapsule surface. (C) 2008 Society of Chemical Industry.