Fabrication and characterization of nanoencapsulated epoxy resin/crosslinked PMMA shells with in situ polymerization via phase inversion emulsion (PIE) method

ABSTRACT Encapsulated epoxy resin healing agents with poly(methyl methacrylate (PMMA) as a thermoplastic polymeric shell are suffered from leakage of the core after a while. This problem leads to loss of their performance and its ability in self‐healing systems. One way to stop or reduce the leakage of the core is crosslinking the PMMA shell. In this study, nanoencapsulation of epoxy healing agent with crosslinked PMMA as shell was carried out by in situ polymerization via phase inversion emulsion method. Ethylene glycol dimethacrylate was employed as crosslinking agent. Nonionic (SPAN 60) and ionic (sodium dodecyl sulfate) surfactants were used for competitive adsorption and phase inversion in emulsion system. Chemical structures, morphologies, and thermal properties of nanocapsules were characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis, respectively. SEM investigations showed that nanocapsules had a particle size of less than 100 nm with a narrow particle size distribution. Efficiency of nanoencapsulation was equal to 83.5%. And synthesized nanocapsules had at least 37% core contents. Nanocapsules with crosslinked shell were able to maintain liquid core up to 18 weeks, while, noncrosslinked shell lost core content after 14 weeks. It seems that low crosslink density has no effect on capsule durability. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137 , 48793.