Cellulose Succinate as a Bio-Based Anionic Polyelectrolyte: Charge-Driven Gelation and Electrostatic Complexation with Aliphatic Diamines

High Resolution Image Download MS PowerPoint Slide Bio-based polyelectrolytes capable of controllable electrostatic interactions are of increasing interest for sustainable soft and responsive materials. In this study, cellulose was chemically modified via esterification with succinic anhydride to yield cellulose succinate (CS), conferring anionic polyelectrolyte character with tunable charge-mediated interactions. Two model aliphatic diamines, ethylenediamine (EDA) and 1,6-diaminohexane (HDA), were employed to systematically investigate electrostatically driven gel formation between CS and cationic species at varying −COOH:NH 2 stoichiometric ratios. Comprehensive characterization, including Fourier transform infrared spectroscopy, solid-state cross-polarization/magic angle spinning 13 C nuclear magnetic resonance spectroscopy, X-ray diffraction, thermogravimetric analysis, zeta potential, and scanning electron microscopy, confirmed successful succinylation and elucidated the structure–property relationships governing gel formation. Gelation was governed by electrostatic complexation between carboxylate groups (−COO – ) of CS and protonated ammonium groups (R-NH 3 + ) of diamines, with bifunctional diamines acting as physical cross-linkers. The resulting hydrogels exhibited pH-responsiveness driven by protonation–deprotonation equilibria, while the hydrophobicity and chain length of the diamine modulated network morphology, thermal stability, swelling, and compressive strength. This work establishes CS as a versatile bio-based anionic polyelectrolyte platform and provides fundamental insights into charge-mediated interactions that can guide the design of next-generation sustainable hydrogels employing benign cross-linkers.