Fast-Photocurable, Mechanically Robust, and Malleable Cellulosic Bio-Thermosets Based on Hindered Urea Bond for Multifunctional Electronics

Malleable thermosets as dynamic covalent cross-linked polymers, simultaneously possessing the advantages of thermosets and thermoplastics, have attracted considerable attention. Although several reprocessing concepts have been demonstrated, the fabrication of fast-curing bio-based strong and tough malleable thermosets for advanced applications in electronics remains a great challenge. Herein, a novel construction strategy of combining hindered urea bonds (HUB) and radical polymerization is developed to prepare fast-photocurable and mechanically robust cellulose-based malleable bio-thermosets (CMTs). In this strategy, the functional cellulose macromonomer simultaneously has acrylate groups and HUB is first synthesized and employed as a macro-crosslinker to react with plant oil-based monomer to construct the malleable bio-thermosets with soft (plant oil-based polymer) and hard (rigid cellulose) phase architecture through the fast photocuring. The CMTs exhibit excellent flexibility and high toughness (2.89 MJ m-3), and the introduction of dynamic HUB endows the CMTs with excellent malleability and reprocessability by heating compression molding or solvent regeneration, the recovery efficiency reached 94.7%. More impressively, the CMTs can be used as substrates to fabricate CMTs/silver composite for anti-icing or de-icing devices, and CMTs-based capacitive sensors for monitoring environmental humidity or human health. This work paves a new strategy to develop new-generation fast-photocurable mechanically robust, malleable bio-thermosets for multifunctional electronic devices. The fast-photocuring cellulosic malleable bio-thermosets (CMTs) with excellent mechanical properties, 3D printability, and reprocessing ability are developed by combination of hindered urea bonds and UV light-induced radical polymerization. The flexible CMTs can be used as sustainable substrates to fabricate CMTs/silver composite for electric heating devices, and capacitive sensor for monitoring environment humidity, human respiration, and motions.image

Automated summary

This study presents a novel construction strategy combining hindered urea bonds and radical polymerization to prepare fast-curing cellulose-based malleable bio-thermosets. The resulting materials exhibit excellent mechanical properties, malleability, and reprocessing ability, and can be used in various electronic devices.