ABSTRACT
Abstract ...................................................................................................................76 5.1 Introduction ...................................................................................................76 5.2 History of Hydrogels .....................................................................................78 5.3 What Are Hydrogels? ....................................................................................79 5.4 Gelling Seaweed Polysaccharides .................................................................80 5.5 Preparation of New Hydrogel Materials .......................................................81 5.6 Conclusions ...................................................................................................89 Acknowledgement ..................................................................................................90 Keywords ................................................................................................................90 References ...............................................................................................................90
Seaweed polysaccharides-based hydrogels constitute a cluster of potential materials, used in several biomedical areas, and are still developing for new promising applications. The seaweed polysaccharides namely agar, carrageenan, agarose, and alginate are the attractive materials for food, textile, pharmaceutical, and biomedical applications. These are obtainable only from the seaweed resource, except for alginates which can also be produced from bacteria. Agar and carrageenans are obtained from the red seaweeds (Rhodophyta), while the alginates are isolated from brown seaweeds (Phaeophyta). Recently, several new hydrogel materials with new functionality, pH-sensitive hydrogel networks, and thermally stable hydrogel network consisting of seaweed polysaccharides and their blends/composites were synthesized in our laboratory. Several techniques, such as grafting, blending/composites, and cross linking were developed for the preparation of new hydrogel materials. These hydrogels were investigated using dynamic oscillatory measurements (Rheology), thermal (DSC, TGA), syneresis measurement in gel samples, moisture content, morphological (SEM), XRD, swelling measurements, bulk density, true density, pore volume, and porosity on the dried samples. These hydrogel materials exhibited considerable thermal stability, pH-responsiveness in aqueous media, and showing super absorbency in different pH solutions. All these new properties predispose these modified products to potential applications in various domains, including ingestible and non-ingestible ones. Hydrogel materials with balanced hydrophobicity/hydrophilicity, can offer desirable release rates, swelling, and dissolution profiles.
