Synthesis of Cloisite 30B-acrylamide/acrylic acid nanogel composite for self-healing purposes

Abstract In the present study, Cloisite 30B nanoclay was modified to prepare a nanogel composite based on acrylic acid (AA) and acrylamide (AAm) through in-situ copolymerization. The prepared nanogel composites were cross-linked and subsequently embedded within a commercial epoxy resin to develop a self-healing epoxy-based coating. The nanogel composites were assessed using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE-SEM). FTIR results confirmed a successful nanogel composite synthesis while the XRD results revealed the increase of the interlayer space of modified nanoclay leading to better dispersion in nanogel, which was also corroborated by TEM. The swelling ratio of the nanogel composite was evaluated to investigate the effect of the crosslinking agent on the swelling of the nanogel. The composite incorporation influence on the properties of the epoxy-based coatings was studied through the pull-off adhesion and elongation at break assessments. The results revealed the nanogel composite embedment within the epoxy coatings slightly decreased the mechanical properties. The self-healing performance of the nanogel incorporated epoxy-based coating was evaluated by electrochemical tests. The obtained results confirmed that the epoxy coating containing 0.5 wt% of nanogel composite provided the highest corrosion resistance after damages with the self-healing efficiency of 99.88%.