Loading...

Partially hydrolyzed crosslinked alginate-graff-polymethacrylamide as a novel biopolymer-based superabsorbent hydrogel having pH-responsive properties

Pourjavadi, A ; Sharif University of Technology | 2005

318 Viewed
  1. Type of Document: Article
  2. DOI: 10.1007/BF03219014
  3. Publisher: Polymer Society of Korea , 2005
  4. Abstract:
  5. In this study, a series of highly swelling hydrogels based on sodium alginate (NaAlg) and polymethacrylamide (PMAM) was prepared through free radical polymerization. The graft copolymerization reaction was performed in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator and N,N'-methylenebisacrylamide (MBA) as a crosslinker. The crosslinked graft copolymer, alginate-graft-polymethacrylamide (Alg-g-PMAM), was then partially hydrolyzed by NaOH solution to yield a hydrogel, hydrolyzed alginate-graft-polymethacrylamide (H-Alg-g-PMAM). During alkaline hydrolysis, the carboxamide groups of Alg-g-PMAM were converted into hydrophilic carboxylate anions. Either the Alg-g-PMAM or the H-Alg-g-PMAM was characterized by FTIR spectroscopy. The effects of the grafting variables (i.e., concentration of MBA, MAM, and APS) and the alkaline hydrolysis conditions (i.e., NaOH concentration, hydrolysis time, and temperature) were optimized systematically to achieve a hydrogel having the maximum swelling capacity. Measurements of the absorbency in various aqueous salt solutions indicated that the swelling capacity decreased upon increasing the ionic strength of the swelling medium. This behavior could be attributed to a charge screening effect for monovalent cations, as well as ionic crosslinking for multivalent cations. Because of the high swelling capacity in salt solutions, however, the hydrogels might be considered as anti-salt superabsorbents. The swelling behavior of the superabsorbing hydrogels was also measured in solutions having values of pH ranging from 1 to 13. Furthermore, the pH reversibility and on/off switching behavior, measured at pH 2.0 and 8.0, suggested that the synthesized hydrogels were excellent candidates for the controlled delivery of bioactive agents. Finally, we performed preliminary investigations of the swelling kinetics of the synthesized hydrogels at various particle sizes. © 2005 Polymer Society of Korea
  6. Keywords:
  7. Acrylamide derivative ; Alginic acid ; Anion ; Biopolymer ; Carboxylic acid derivative ; Cation ; Copolymer ; Sodium hydroxide ; Aqueous solution ; Concentration (parameters) ; Cross linking ; Fourier transformation ; Hydrogel ; Hydrolysis ; Ionic strength ; Kinetics ; Measurement ; Particle size ; pH ; Polymerization ; Reaction analysis ; Synthesis ; Temperature
  8. Source: Macromolecular Research ; Volume 13, Issue 1 , 2005 , Pages 45-53 ; 15985032 (ISSN)
  9. URL: https://link.springer.com/article/10.1007/BF03219014