Fabrication of a strong, tough, recyclable, and multifunctional bio-based epoxy vitrimer via constructing polyarylation-enhanced dynamic networks

The fabrication of eco-friendly bio-based epoxy resins is of critical importance for addressing the excessive consumption of petroleum resources and the release of harmful substances caused by petroleum-based thermosetting epoxy resins. However, the non-recyclability and poor mechanical properties of bio-based epoxy resins hinder their further development and application. Herein, a strong, tough, recyclable, and multifunctional bio-based epoxy vitrimer is prepared using epoxidized soybean oil (ESO) and lignin-based aromatic monomers of vanillyl alcohol, guaiacol, and vanillin. These lignin-based aromatic monomers provide bio-based aromatic building blocks for the synthesis of bisguaiacol F diamine vanillin (BGAV) with dynamic imine bonds, which is employed as a curing agent for ESO to fabricate a bio-based epoxy vitrimer incorporating a dynamic network. The BGAV forms rigid polyaromatic segments in the network to enhance the stability of the polymer, thereby leading to a high mechanical strength of 21.81 MPa for the epoxy vitrimer. Moreover, the hydrogen bonds in the network serve as sacrificial bonds to increase the ability of energy dissipation, thereby resulting in excellent toughness of 27.53 MJ m^-3 for the epoxy vitrimer. Additionally, the reversible reconstruction of dynamic imine bonds within the network endows the vitrimer with favorable self-healing properties and recyclability. Furthermore, the vitrimer also exhibits outstanding antibacterial properties, mold resistance, photothermal conversion performance, water resistance, and bonding performance. This work provides an effective approach for the development of recyclable bio-based epoxy resins with exceptional mechanical properties and multifunctionality.