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

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.

Eco-Friendly Sustainable Poly(benzoxazine-co-urethane) with Room-Temperature-Assisted Self-Healing Based on Supramolecular Interactions.

This work is an attempt to develop bio-based eco-friendly poly(benzoxazine-co-urethane) [poly(U-co-CDL-aee)] materials using cardanol-based benzoxazines (CDL) and hexamethylene diisocyanate (HMDI) to check their self-healing ability and thermal properties. CDL monomers were synthesized using cardanol, amino ethoxyethanol (aee) or 3-aminopropanol (3-ap), and paraformaldehyde through the Mannich reaction. Later, CDL-aee or CDL-3-ap monomers were copolymerized with a urethane precursor (HMDI), followed by ring-opening polymerization through thermal curing. The thermal properties of poly(U-co-CDL) were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The self-healing behavior of the bio-based poly(U-co-CDL) was checked by applying a mild external pressure. The results revealed that the developed poly(U-co-CDL) showed repeatable self-healing ability due to supramolecular hydrogen-bonding interactions. Further, the self-healing ability of poly(U-co-CDL) was studied using density functional theory (DFT). From the above results, the developed material with superior self-healing ability can be used in the form of self-healing coatings and composites for various applications with extended shelf-life and reliability.