BACKGROUND: As part of an ongoing research and development programme of our laboratory on functional modification of seaweed polysaccharides for preparing hydrogels with improved properties, we report herein the preparation of a robust hydrogel system based on grafting of agar and sodium alginate blend (Agar/Na‐Alg) with acrylamide (AAm) to obtain the copolymer Agar/Na‐Alg‐graft‐PAAm.

RESULTS: A robust hydrogel system with superior absorbency and pH resistance has been developed based on a PAAm‐grafted seaweed polysaccharide blend of Agar/Na‐Alg. The blend (Agar/Na‐Alg) and grafted product (Agar/Na‐Alg‐graft‐PAAm) were evaluated using Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, swelling capacity, rheology and scanning electron microscopy. The swelling capacity of the grafted copolymer exhibited an enhancement over that of the blend from 14 to 24 g g⁻¹ in acidic medium. The blend and grafted copolymer produced hydrogels with lower gelling points of 31 and 29 °C and gel strengths were 170 and 120 g cm⁻², respectively.

CONCLUSION: This study constitutes an example of value addition of seaweed polysaccharides targeting new applications. The copolymer hydrogel may be useful in health, personal care and agricultural applications. Copyright © 2007 Society of Chemical Industry