Synthesis of Vanillin-Based Polyimine Vitrimers with Excellent Reprocessability, Fast Chemical Degradability, and Adhesion

A series of biobased polyimine vitrimers was synthesized by condensation between a dialdehyde or trialdehyde derived from vanillin and a commercial biobased aliphatic amine. The structure, thermal stability, mechanical properties, and reprocessability of vitrimers with different cross-linking degrees were investigated. The results indicated that the glass transition temperature (Tg) of vitrimers increased with the increase of cross-linking density. In addition, the vitrimers showed good malleability and recyclability even with high cross-linking degree based on fast imine metathesis. The degradation test of polyimine vitrimers suggested that the decomposition rate increased with the rising temperature, and the vitrimer degraded rapidly in 0.1 M HCl aqueous solution. After acid degradation, the aldehyde monomer was precipitated, and it can be reused to prepare a vitrimer to realize the closed-loop cycle. Finally, the biobased polyimine vitrimers can be used as adhesives, and the shear tensile strength showed that the bond strength of the vitrimer was up to 6.79 MPa.