Preparation and Characterization of Glutaraldehyde-Crosslinked Kappa Carrageenan Hydrogel

Glutaraldehyde-crosslinked kappa carrageenan hydrogel was prepared using glutaraldehyde (GA) as the crosslinking agent. Kappa carrageenan film obtained from extraction of Kappaphycus alvarezii seaweed was immersed in GA solution (1-5 wt%) for 2 min and then cured at 110 o C for 25 min. The obtained crosslinked film was washed and soaked in the ethanol to remove the unreacted GA. The obtained film was air dried at room temperature to a constant weight. The infrared spectra, thermal analysis, and the value of swelling degree of obtained hydrogel showed that kappa carrageenan was able to be crosslinked using GA by film immersion and high temperature curing method without catalyst presence. GA concentration less than 0.027 g GA/g polymer was not able to crosslink hydroxyls group of carrageenan. The swelling degree in water media decreased up to 60% with increasing GA concentration from 3% to 5%. The kappa carrageenan hydrogel was found to be pH sensitive.