Sustainable polyimine vitrimers derived from biological resources with high performance and self-healing properties

Thermosetting polymers are characterized by high mechanical performance, thermal resistance, chemical resistance, and good dimensional stability during processing. However, their inability to be repaired and recycled creates an environmental burden. Vitrimers are an important technique to overcome this issue. In this study, a vitrimer derived from biological resources was developed and can be a candidate to replace thermosetting polymers. First, a trifunctional aldehyde was synthesized by nucleophilic substitution of vanillin derived from lignin with 1,3,5-tris(bromomethyl)benzene. Subsequently, it was reacted with commercially available amines to prepare a series of polyimine vitrimers. Dynamic mechanical analysis showed that when the aldehyde and amine were reacted at the stoichiometric ratio, the obtained vitrimer had the largest storage modulus (8.80 GPa) and crosslinking density (1.18 mol/L). Self-healing test showed that the tensile strength of the vitrimer can remain as high as 70.16 MPa after two repair cycles. These characteristics exhibit superior performance in comparison with prior studies. This study successfully developed the vitrimers derived from biological resources with excellent mechanical property and self-healing effect, which is renewable and has a strong potential to replace thermosetting polymers in the future.