Biodegradable and reprocessable cellulose-based polyurethane films for bonding and heat dissipation in transparent electronic devices

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

“…As shown in Figure a, the characteristic absorption bands at 3350 and 1530 cm −1 were attributed to the stretching vibrations of ─NH─ of amide groups and ─C═O─ of urea carbonyl groups, respectively, indicating the successful construction of HUB. [ 35,42 ] The characteristic absorption bands at 2270 and 3460 cm −1 corresponding to the stretching vibrations of ─NCO and ─OH disappeared in HTC with the emergence of a new characteristic absorption peak at 1637 cm −1 corresponding to the vinyl bonds (─C═C─), which indicated the successful synthesis of the HTC macromonomer. Subsequently, the HTC macromonomer was used as a functional macro‐crosslinker to cure with plant oil‐based monomer (LMA) to construct the “soft” and “hard” phase alternated cellulose‐based malleable bio‐thermosets (CMTs) via one‐step UV light‐induced radical polymerization (Figure 1a, Step 2).…”

“…[32,33] However, the inherent polarity and hydrophilicity of cellulose resulted in weak interaction and poor compatibility with non-polar and hydrophobic thermosets matrix. [34,35] Generally, the introduction of functional groups (such as vinyl bonds, ester groups, and hindered tertiary amine groups) onto the cellulose backbone by chemical modification could improve its hydrophobicity as well as achieve the fastphotocuring ability and malleability. [36][37][38][39] Nevertheless, owing to the crystal structure and rigidity of cellulose, the excessive introduction of cellulose would increase the brittleness of thermosets.…”