Reactive SAH-Based Deep Eutectic Solvent Enables Efficient Carboxylation of Bamboo Fibers with Preserved Structure...

Selective chemical modification of cellulose in lignocellulosic fibers without disrupting the native hierarchical structure remains a central challenge in polysaccharide chemistry. Herein, we report a reactive succinic anhydride-based deep eutectic solvent (SAH-DES) strategy. The SAH-DES system, comprising choline chloride, succinic anhydride, and water (1:1:1 molar ratio), forms a robust hydrogen-bonded network to stabilize anhydride reactivity and suppress hydrolysis. Under optimized conditions (100 °C, 3 h), carboxylated bamboo fibers (C-BFs) achieved a high carboxyl content of 1.01 ± 0.03 mmol/g while retaining excellent tensile strength (2104 ± 237 MPa). The introduced carboxyl groups enabled uniform deposition of conductive materials (Ag/Ni nanoparticles, polypyrrole), resulting in a high electrical conductivity of 34,271 ± 1266 S/m. This study demonstrates that water-regulated reactivity in deep eutectic solvents provides a pathway for selective cellulose esterification, offering mechanistic insight into structure-reactivity relationships of polysaccharides in confined solvent systems.