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

Abstract 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.