Graft Copolymerization Onto Starch. 3: Grafting of Acrylamide Using Ceric Ion Initiation and Preparation of Its Hydrogels

Athawale, Vilas D.; Vidyagauri, V. Lele

doi:10.1002/(sici)1521-379x(199810)50:10<426::aid-star426>3.0.co;2-#

Cited by 70 publications

(45 citation statements)

References 11 publications

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“…Such behaviors are reported by other investigators. [22][23][24] Effect of APS Concentration 7 7 The relationship between the initiator concentration and water absorbency values was studied by varying the APS concentration from 0.09 to 0.35 mol/L ( Figure 5). According to Figure 5, the absorbency is increased with increasing the APS concentration from 0.09 up to 0.22 mol/L and then, it is decreased considerably with a further increase in the amount of monomer.…”

Section: Resultsmentioning

confidence: 99%

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

2005

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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.

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Section: Resultsmentioning

confidence: 99%

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

2005

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“…Starch which is a low cost abundantly available renewable biopolymer on modification may develop properties comparable to synthetic petroleum-based polymers [1,2] Chemical grafting [3][4][5][6][7] is one of the popular methods for modifying structure and properties of biopolymers. Vinyl grafting on to the polysaccharides improves their shelf life against biodegradation, thermal stability and metal ion binding ability and therefore grafted polysaccharides have a wide range of industrial utility [8].…”

Section: Introductionmentioning

confidence: 99%

Peroxydisulfate initiated synthesis of potato starch-graft-poly(acrylonitrile) under microwave irradiation

Singh¹,

Tiwari²,

Pandey³

et al. 2007

Express Polym. Lett.

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Abstract. Potato starch-graft-poly(acrylonitrile) could be efficiently synthesized using small concentration of ammonium peroxydisulfate (0.0014 M) in aqueous medium under microwave irradiation. A representative microwave synthesized graft copolymer was characterized using Fourier Transform Infrared Spectroscopy, X-ray Diffraction, Scanning Electron Microscopy and Thermogravimetric Analysis. Under microwave conditions oxygen removal from the reaction vessel was not required and the graft copolymer was obtained in high yield using very small amount of ammonium peroxydisulfate, however using the same amount of ammonium peroxydisulfate (0.0014 M) on thermostatic water bath no grafting was observed up to 98°C (even in inert atmosphere). Raising the concentration of the initiator to 0.24 M resulted into 10% grafting at 50°C but in inert atmosphere. The viscosity/shear stability of the grafted starch (aqueous solution) and water/saline retention ability of the microwave synthesized graft copolymer were also studied and compared with that of the native potato starch.

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“…The swelling-loss after the maximum may be attributed to (a) preferential homopolymerization over graft copolymerization, (b) increase in viscosity of the medium, which restricts the movement of free radicals and monomer molecules, and (c) the enhanced chance of chain transfer to monomer molecules. Other investigators [24][25][26] reported similar conclusions.…”

Section: Methodsmentioning

confidence: 99%

Modified carrageenan. 6. crosslinked graft copolymer of methacrylic acid and kappa-carrageenan as a novel superabsorbent hydrogel with low salt- and high pH-sensitivity

2005

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A novel, polysaccharide-based, superabsorbent hydrogel was synthesized through crosslinking graft copolymerization of methacrylic acid (MAA) onto kappa-carrageenan (κC), using ammonium persulfate (APS) as a free radical initiator in the presence of methylenebisacrylamide (MBA) as a crosslinker. A proposed mechanism for κC-g-polymethacrylic acid (κC-g-PMAA) formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The effect of grafting variables, including MBA, MAA, and APS concentration, was systematically optimized to achieve a hydrogel with the maximum possible swelling capacity. The swelling kinetics in distilled water and various salt solutions were preliminarily investigated. Absorbency in aqueous salt solutions of lithium chloride, sodium chloride, potassium chloride, calcium chloride, and aluminum chloride indicated that the swelling capacity decreased with increased ionic strength of the swelling medium. This behavior can be attributed to the charge screening effect for monovalent cations, as well as ionic crosslinking for multivalent cations. The swelling of superabsorbing hydrogels was measured in solutions with pH ranging from 1 to 13. In addition, the pH reversibility and on-off switching behavior, at pH levels of 3.0 and 8.0, give the synthesized hydrogels great potential as an excellent candidate for the controlled delivery of bioactive agents.

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Graft Copolymerization Onto Starch. 3: Grafting of Acrylamide Using Ceric Ion Initiation and Preparation of Its Hydrogels

Cited by 70 publications

References 11 publications

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

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

Peroxydisulfate initiated synthesis of potato starch-graft-poly(acrylonitrile) under microwave irradiation

Modified carrageenan. 6. crosslinked graft copolymer of methacrylic acid and kappa-carrageenan as a novel superabsorbent hydrogel with low salt- and high pH-sensitivity

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