Development and Physicochemical Characterization of Chitosan/Glucomannan and Chitosan/PVP Composite Beads With Urea Incorporation

ABSTRACT Hydrogels are three‐dimensional, crosslinked, hydrophilic polymers with exceptional water‐absorption capabilities, making them promising materials for controlled‐release applications. This study focuses on the enhancement and characterization of composite hydrogel beads based on chitosan (Ch) combined with glucomannan (G) or polyvinyl pyrrolidone (PVP), with and without urea incorporation, for potential application in controlled‐release systems. Four formulations were successfully fabricated: ChG, ChGu, ChP, and ChPu. Fourier‐transform infrared spectroscopy confirmed hydrogen‐bond formation between chitosan and the secondary polymers via characteristic peak shifts. Differential scanning calorimetry revealed new endothermic peaks in composites (121°C for ChP; 108°C and 143°C for ChG), confirming the formation of new polymer networks with enhanced thermal stability. Swelling studies demonstrated pH‐dependent behavior: ChP composites exhibited continuous swelling up to 120% at neutral pH, while ChG composites showed rapid initial swelling followed by degradation. Gel fraction analysis quantified network integrity, with ChP exhibiting the highest value (68.02% ± 3.60%), indicating dense crosslinking, whereas ChG showed a moderate gel fraction (32.50% ± 3.16%). Urea incorporation consistently reduced gel fraction (ChPu: 54.40% ± 3.44%; ChGu: 27.50 ± 3.55%), demonstrating its role as a network modulator through hydrogen bond disruption—the ‘salting‐out’ effect. Water vapor adsorption studies revealed stable profiles over seven days (97.34%–99.92%), with ChG‐based composites showing slightly higher adsorption due to their more open network structure. These findings demonstrate that chitosan/glucomannan and chitosan/PVP composites exhibit distinct, tunable physicochemical properties that can be modulated by polymer selection and urea incorporation, positioning them as promising candidates for controlled‐release systems in agricultural and biomedical applications.