Biobased Polybenzoxazine Vitrimer with Imine Bonds: Shape Memory, Reprocessing, and Degradation

A biobased reprocessable and degradable polybenzoxazine vitrimer was prepared by introducing dynamic imine bonds. An aldehyde-containing benzoxazine monomer (VSA) was synthesized through the Mannich reaction of vanillin, stearylamine, and paraformaldehyde, and then VSA was reacted with 1,12-dodecanediamine to prepare an imine-containing benzoxazine monomer (VSA-dda). The curing behaviors of VSA-dda were characterized by in situ Fourier-transform infrared spectroscopy and differential scanning calorimetry. The dynamic exchange reaction of imine bonds within the cross-linked network of polybenzoxazine (PVSA-dda) was studied by stress relaxation experiments. Due to the presence of imine bonds, PVSA-dda could be reprocessed by hot-pressing at 140 °C under 2 MPa. PVSA-dda exhibited a shape memory property and could recover its original shape by heating at 100 °C. The degradation performance of PVSA-dda was investigated under various conditions, and the results showed that PVSA-dda could be degraded within 29 min in an acidic solution of tetrahydrofuran and water at 50 °C.