Synthesis of innovative epoxy resin and polyamine hardener microcapsules and their age monitoring by confocal Raman imaging

Abstract

Abstract We present an innovative breakthrough encompassing synthesis, characterization, and age monitoring of epoxy resin and polyamine hardener microcapsules to form a dual‐component system for self‐healing anticorrosion coatings. The epoxy resin microcapsules (ER‐MC) are fabricated through oil–water emulsion and in situ polymerization, with poly (urea‐formaldehyde‐melamine) as shell material and a mixture of epoxy resin and n ‐butyl glycidyl ether as core material. Modified aliphatic fast reactive polyamine hardener is microencapsulated with polymethylmethacrylate as shell using double emulsion and solvent evaporation method (PAH‐MC). Characterization includes optical microscopy, scanning electron microscopy, and particle size analyzer utilizing laser diffraction. The resulting microcapsules exhibited spherical shape with smooth surface devoid of porosity. Fourier transform infrared spectroscopy‐attenuated total reflection is utilized to confirm encapsulation by identifying the chemical structures of both microcapsule constituents. The thermogravimetric analysis further confirms the core content of microcapsules obtained from solvent extraction. ER‐MC contains approximately 66 wt %, while PAH‐MC stands 40 wt %, both showcasing remarkable thermal stability below 200°C. A ten‐month storage period fails to diminish the presence of the healing agents encapsulated within the polymeric walls, which is revealed by Raman spectroscopy utilizing 2D compositional mapping. This research demonstrates the viability of creating dual microcapsules and exemplify their potential for developing self‐healing coatings with dual‐component film‐forming healing agents.