A reversible healable epoxy network containing dynamic weak covalent crosslinks

摘要

A straightforward pathway is introduced to synthesize a Diels-Alder (DA)-crosslinked epoxy material with glass transition-induced shape recovery capacity, via combination of an epoxy polymer synthesized from bio-based furfurylamine with a telechelic maleimide-ended oligomer derived from 4,4'-methylenebis(N-phenylmaleimide) and 2,2-(ethylenedioxy)diethanethiol. The use of such a BMI-modified crosslinker overcame the poor solubility and brittleness of materials resulting from the BMI analogue. The formation of the precursors and DA crosslinked network, its recyclability, thermo-reversibility and shape memory-aided scratch healability were visualized qualitatively and studied by FT1R and ~1H NMR spectrometry, differential scanning calorimetry, optical microscopy, scanning electron microscopy and tensile measurements. Scratch healing was possible via a two step heating process at 120 °C for 1 h and subsequently at 70 °C for 6 h, reaching a relatively good healing efficiency, evaluated by a tensile strength recovery of approximately 70%.