Physically Crosslinked Poly (Vinyl Alcohol)/Kappa-Carrageenan Hydrogels: Structure and Applications

• Main Authors: Catalin Croitoru, Mihai Alin Pop, Tibor Bedo, Mihaela Cosnita, Ionut Claudiu Roata, Iosif Hulka
• Format: Article
• Language: English
• Published: MDPI AG 2020-03-01
• Series: Polymers
• Subjects: poly (vinyl alcohol); k-carrageenan; physical crosslinking; freeze-thaw cycles; ftir spectroscopy; thermal analysis; sorption
• Online Access: https://www.mdpi.com/2073-4360/12/3/560
• ISSN: 2073-4360

This paper discusses the structure morphology and the thermal and swelling behavior of physically crosslinked hydrogels, obtained from applying four successive freezing−thawing cycles to poly (vinyl alcohol) blended with various amounts of κ-carrageenan. The addition of carrageenan in a weight ratio of 0.5 determines a twofold increase in the swelling degree and the early diffusion coefficients of the hydrogels when immersed in distilled water, due to a decrease in the crystallinity of the polymer matrix. The diffusion of water into the polymer matrix could be considered as a relaxation-controlled transport (anomalous diffusion). The presence of the sulfate groups determines an increased affinity of the hydrogels towards crystal violet cationic dye. A maximum physisorption capacity of up to 121.4 mg/g for this dye was attained at equilibrium.