Amine-Structure-Regulated Vanillin-Derived Imine-Cross-Linked Networks for Reprocessable, Self-Healing, and Chemically Recyclable Thermosets

Vanillin offers a renewable aromatic platform for this purpose because it can introduce rigidity while providing functional groups for dynamic network construction. Here, we report a series of vanillin-derived imine-cross-linked polymer networks (VD-TAM) prepared from a benzoxazine-containing dialdehyde monomer (VD), decanediamine (DM), and tris(2-aminoethyl)amine (TAM).

By fixing the aldehyde/amine functional-group ratio at 1:1 and the VD content while varying the relative contributions of flexible DM segments and trifunctional TAM junctions, the network structure was systematically regulated. This design allowed the amine structure-dependent balance between network rigidity and imine-exchange dynamics to be evaluated. Increasing the TAM content raised the glass-transition temperature from 49.3 to 72.2 °C, the DMA-derived effective cross-link density from 5.31 × 10^–4 to 16.43 × 10^–4 mol cm^–3, and the tensile strength from 40.37 to 56.33 MPa, while decreasing the elongation at break from 124.47 to 7.29%.