Self-adhesive, ionic-conductive, mechanically robust cellulose-based organogels with anti-freezing and rapid recovery properties for flexible sensors.

Cellulose-based functional gels have received considerable attention because of their good mechanical properties, biocompatibility, and low cost. However, the preparation of cellulose gels with self-adhesion, mechanical robustness, ionic conductivity, anti-freezing ability, and environmental stability remains a challenge. Here, gallic acid esterified microcrystalline cellulose (MCC-GA) was obtained by grafting gallic acid (GA) onto the macromolecular chains of microcrystalline cellulose (MCC) through a one-step esterification method. Then the prepared MCC-GA was dissolved in Lithium chloride/dimethyl sulfoxide (LiCl/DMSO) system and polymerized with acrylic acid (AA) to prepare a multi-functional cellulose-based organogel. The prepared MCC-GA/polyacrylic acid (PAA) organogels exhibited enhanced interfacial adhesion through hydrogen bonding, π-π interactions, and electrostatic interactions. Additionally, the MCC-GA/PAA organogels could withstand 95 % of the compressive deformation and rapidly self-recover owing to chemical cross-linking and dynamic non-covalent interactions. The organogels also exhibited excellent anti-freezing properties (up to -80 °C), solvent retention, and ionic conductivity. Considering its excellent overall performance, the MCC-GA/PAA organogel was used as an effective flexible sensor for human motion detection and is expected to play an important role in the future development of flexible bioelectronics.