Gel–Sol Transition of Vanillin-Based Polyimine Vitrimers: Imparting Vitrimers with Extra Welding and Self-Healing Abilities

Vitrimers are cross-linked networks through reversible dynamic covalent bonds. Usually, self-healing of vitrimers are realized by rearrangement of the networks under high temperature (>150 °C) and high pressure. The vitrimers that can be recovered under milder conditions have rarely been reported. In this work, interesting solvent-induced recyclable polyimine vitrimers derived from vanillin were first developed. Their recovery processes can be carried out through an unexpectedly fast and unusual gel–sol transition (less than 30 min) with the help of a few solvents. Thanks to this special ability, the polyimine vitrimers not only can be reprocessed by traditional hot-press and degradation, but also exhibit solvent-induced welding and self-healing abilities at room temperature. Moreover, aldehyde monomers can be recycled through chemical degradation without further separation in the mixture of recycled monomers, and the effects of aldehyde monomers on the properties of as-prepared polyimine vitrimers were first studied in detail.