PH-responsive ampholytic regenerated cellulose hydrogel integrated with carrageenan and chitosan

Abstract

Regenerated cellulose (RC) that is produced from ‘green’ alkali/urea system has been extensively studied and fabricated into hydrogel. The versatility of RC products can be combined with other natural polymers to enhance their applicability. In this work, ampholytic polyelectrolyte RC-hydrogels were fabricated successfully via a facile technique of homogenous RC/chitosan(CS)/carrageenan(CG) in NaOH/urea aqueous system with no phase separation occurs between anionic and cationic polymers. The chemical structure of the hydrogels were characterized by using ATR-FTIR and XRD while for morphological structure, VPSEM was performed. The swelling kinetics, swelling capacity, water uptake in different pH media, gel fraction and gel degradation of hydrogels were determined. The swelling kinetics of hydrogels followed the first-order kinetic for swelling in distilled water and different pH media with all R2 > 0.9. The addition of CS into the hydrogels also gave the highest swelling capacity and gel fraction that reached 104.30% and 97.93%, respectively. The experimental results demonstrated that ampholytic RC/CG/CS hydrogels had good water uptake in low pH solution due to macromolecular chain relaxation of CS. However, under high pH, low water uptake was recorded in all resulting hydrogels due to hydrogel’s internal colloidal shrinkage due to amine group in CS accumulation and free release of sulfate group in CG. The degradation test revealed that hydrogels without CS had the huge dry weight loss after 24 days at 9.26% and all hydrogels were degraded according to surface erosion manner. Availability of data and materialNot applicable.