Author:

Keywords:

Science & Technology, Physical Sciences, Chemistry, Applied, Chemistry, Organic, Polymer Science, Chemistry, Sodium alginate, Homopolymeric fractions, PNIPAAm, Hydrogels, SEM, POLYMER NETWORK HYDROGELS, LESSONIA-VADOSA, SEMI-IPN, ACID, POLYSACCHARIDES, TEMPERATURE, HYDROLYSIS, DELIVERY, Acrylamides, Acrylic Resins, Alginates, Biocompatible Materials, Drug Carriers, Glucuronic Acid, Hexuronic Acids, Humans, Materials Testing, Polymers, Surface Properties, Temperature, 0303 Macromolecular and Materials Chemistry, 0305 Organic Chemistry, 0908 Food Sciences, 3006 Food sciences, 3101 Biochemistry and cell biology, 4004 Chemical engineering

Abstract:

Graft copolymers were prepared by formation of an amide bond between poly-α-l-guluronic acid (MW 24,000), isolated from sodium alginate and the free amino group of PNIPAAm-NH(2). SEM micrographs revealed the formation of a macroscopic network on the surface of the grafted hydrogels with a porosity diameter of 10-20μm. Semi-IPN hydrogels were prepared using different proportions of sodium poly-β-d-mannuronate (MW 21,000), isolated from sodium alginate and cross-linked PNIPAAm-NH(2) polymers. SEM micrographs showed porosities of minor size (∼5μm). Though both types of hydrogels are good water containers, the water retention capacity of graft copolymers is more than 50% higher than that of semi-IPN hydrogels. Both hydrogel types showed significant changes in swelling ratios between 20 and 45°C: the swelling ratio decreases near the LCST of PNIPAAm. The water absorption and retention capacity of graft hydrogels increases with pH, reaching a maximum value at pH 7.0.