EFFECT OF POLYMER COMPOSITION AND TEMPERATURE ON THE RHEOLOGICAL PROPERTIES OF CHITOSAN-CARBOXYMETHYL CELLULOSE HYDROGELS

Abstract

. Introduction. Over the past decade, superabsorbent hydrogels based on natural polymers (cellulose, chitosan) have been widely applied in biomedicine. Despite their high stability and biocompatibility, these hydrogels exhibit several drawbacks associated with insufficient pseudoplasticity and thixotropy. Consequently, the development of hydrogel systems with tailored rheological properties has acquired critical medical relevance. The objective of this study was to develop and comprehensively investigate the rheological properties of hydrogels based on chitosan (CS)  and carboxymethylcellulose (CMC) with different component ratios, as well as to evaluate the effects of shear rate and temperature on their rheological characteristics in order to identify promising formulations for topical application. Results and Discussion. Chitosan/carboxymethylcellulose (CS/CMC) hydrogels with different polymer ratios were investigated by rheometry at temperatures of 20, 25, and 35°C over a shear-rate range of 3-120 s⁻¹. The highest apparent viscosity under all investigated conditions was observed for the CS2.0/CMC0.5 formulation, whereas increasing temperature resulted in a consistent decrease in viscosity. To quantitatively evaluate the rheological behavior, the experimental data were fitted using the Power-law, Herschel-Bulkley, and Casson models. Conclusion. CS/CMC hydrogels exhibited pronounced shear-thinning behavior at 20-35°C and shear rates of 3-120 s⁻¹, facilitating their application to the skin. The CS2.0/CMC0.5 formulation showed the highest viscosity and stable rheological behavior (K = 16.90 Pa·sⁿ, n = 0.389, R² = 0.987 at 25°C), making it a promising matrix for topical hydrogel systems.