Hyperbranched Dynamic Crosslinking Networks Enable Degradable, Reconfigurable, and Multifunctional Epoxy Vitrimer

TLDR

Degradation and reprocessing of thermoset polymers remain intractable challenges for sustainability. The authors propose hyperbranched dynamic crosslinking networks (HDCNs) to transform a petroleum‑based epoxy thermoset into a degradable, reconfigurable, multifunctional vitrimer. HDCNs feature spatially topological crosslinks for solvent adaptation and multiple dynamic linkages that enable reversible behaviors. The vitrimer degrades mildly at room temperature in dimethylacetamide, allows recycling of carbon fiber and epoxy powder, exhibits superior toughness, high flexural modulus, transparency, and fire‑retardancy, can be converted to an elastomeric network by ethanol‑induced ester exchange, and achieves an ultrahigh modulus of 5.45 GPa at −150 °C, positioning it as a sustainable, high‑performance polymer.

Abstract

Abstract Degradation and reprocessing of thermoset polymers have long been intractable challenges to meet a sustainable future. Star strategies via dynamic cross‐linking hydrogen bonds and/or covalent bonds can afford reprocessable thermosets, but often at the cost of properties or even their functions. Herein, a simple strategy coined as hyperbranched dynamic crosslinking networks (HDCNs) toward in‐practice engineering a petroleum‐based epoxy thermoset into degradable, reconfigurable, and multifunctional vitrimer is provided. The special characteristics of HDCNs involve spatially topological crosslinks for solvent adaption and multi‐dynamic linkages for reversible behaviors. The resulting vitrimer displays mild room‐temperature degradation to dimethylacetamide and can realize the cycling of carbon fiber and epoxy powder from composite. Besides, they have supra toughness and high flexural modulus, high transparency as well as fire‐retardancy surpassing their original thermoset. Notably, it is noted in a chance‐following that ethanol molecule can induce the reconstruction of vitrimer network by ester‐exchange, converting a stiff vitrimer into elastomeric feature, and such material records an ultrahigh modulus (5.45 GPa) at −150 °C for their ultralow‐temperature condition uses. This is shaping up to be a potentially sustainable advanced material to address the post‐consumer thermoset waste, and also provide a newly crosslinked mode for the designs of high‐performance polymer.