Vitrimers trigger covalent bonded bio-silica fused composite materials for recycling, reshaping and self-healing applications

Abstract
In this work, a recycling, reshaping, and self-healing strategy was followed for polybenzoxazine through S–S bond cleavage reformation in vitrimers, and the supramolecular interactions are described. The E-ap benzoxazine monomer was synthesized through the Mannich condensation reaction using a renewable eugenol, 3-amino-1-propanol and paraformaldehyde. Furthermore, the E-3ap monomer was reinforced with various weight percentages (5, 10, and 15 wt%) of the thiol-ene group. Various weight percentages of functionalized bio-silica (BS) were also copolymerized with E-3ap (10%-SH) to increase the thermal stability. The structure of the monomers was confirmed by NMR and FT-IR analysis and the thermal properties of the cured materials were analyzed by DSC and TGA. Tensile test was used to study the mechanical property of the poly(E-3ap-co-SH)/BS material. The film was characterized by SEM and optical microscopy to investigate the self-healing properties of the poly(E-3ap-co-thiol-ene)/BS. Moreover, photos and video clips show the self-healing ability of a test specimen. The vitrimer-based renewable polybenzoxazine material exhibits a good recycling, reshaping, and self-healing abilities, and thus is a prime candidate for several industrial and engineering applications.