title: Preparation and characterization of hydrogels based on homopolymeric fractions of sodium alginate and PNIPAAm.
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 10-20 μm. 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 (∼5 μm). 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.
authors.affiliation: Department of Environmental Chemistry, Faculty of Chemistry and Biology, Universidad de Santiago de Chile, Av. B. O'Higgins 3363, Santiago, Chile.
authors.forename: David
authors.initials: D
authors.lastname: Leal
authors.forename: Wim
authors.initials: W
authors.lastname: De Borggraeve
authors.forename: Maria V
authors.initials: MV
authors.lastname: Encinas
authors.forename: Betty
authors.initials: B
authors.lastname: Matsuhiro
authors.forename: Robert
authors.initials: R
authors.lastname: Müller
mesh_terms: D000178:Acrylamides / Q000138:chemical synthesis / Q000737:chemistry; D000180:Acrylic Resins / Q000138:chemical synthesis / Q000737:chemistry; D000464:Alginates / Q000138:chemical synthesis / Q000737:chemistry; D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry; D004337:Drug Carriers / Q000138:chemical synthesis / Q000737:chemistry; D020723:Glucuronic Acid / Q000138:chemical synthesis / Q000737:chemistry; D006603:Hexuronic Acids / Q000138:chemical synthesis / Q000737:chemistry; D006801:Humans; D020100:Hydrogels / Q000138:chemical synthesis / Q000737:chemistry; D008422:Materials Testing; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature
chemical_list: D000178:Acrylamides; D000180:Acrylic Resins; D000464:Alginates; D001672:Biocompatible Materials; D004337:Drug Carriers; D006603:Hexuronic Acids; D020100:Hydrogels; D011108:Polymers; C052970:poly-N-isopropylacrylamide; D020723:Glucuronic Acid