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

TLDR

Vitrimers are cross‑linked networks formed by reversible dynamic covalent bonds, yet their self‑healing typically requires temperatures above 150 °C and high pressure, and recovery under milder conditions has rarely been reported. This study develops solvent‑induced recyclable polyimine vitrimers derived from vanillin. The vitrimers recover through an unexpectedly fast gel–sol transition in less than 30 min with a few solvents, and aldehyde monomers can be recycled via chemical degradation without further separation, whose effects on the polymer properties were investigated. These polyimine vitrimers can be reprocessed by hot‑pressing and degradation, and they exhibit solvent‑induced welding and self‑healing at room temperature, demonstrating the practical advantages of the approach.

Abstract

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.