Polybenzoxazine vitrimer from cardanol based on exchangeable disulfide bonds: reprocessing, recycling, and self-healing and reversible adhesion

Polybenzoxazines (PBZ) are a relatively new class of thermosets with outstanding properties and exceptional molecular design flexibility making possible the use of renewable resources for their synthesis.^1,2 However, similarly to other thermosets such as phenolic and epoxy resins they cannot be recycled and reprocessed. To address this issue, this work details how exchangeable disulfide bonds can be introduced in the chemical structure of a bio-based PBZ network. To this aim, 4-aminophenyl disulfide was reacted with cardanol, a bio-based phenolic compound, to produce the first vitrimer based on PBZ.³ Thanks to the disulfide bond, the novel PBZ was recycled, reshaped, and reprocessed. Interestingly, the material exhibits a fast stress relaxation (18 s. at 120 °C) with low activation energy (64.5 kJ/mol). One of the most amazing features of the material is its reversible and self-healable adhesive properties, showing a straightforward reparation and re-use under mild conditions. This presentation will describe the synthesis and the properties of this new vitrimer.
1. H. Ishida, Handbook of Benzoxazine Resins, Elsevier, Amsterdam, 2011.
2. Y. Lyu and H. Ishida, Prog. Polym. Sci., 2019, 99, 101168
3. A. Trejo-Machin, L. Puchot and P. Verge, Polym. Chem., 2020, DOI: 10.1039/D0PY01239D.