pH sensitivity and swelling behavior of partially hydrolyzed formaldehyde-crosslinked poly(acrylamide) superabsorbent hydrogels

Poly(acrylamide) superabsorbent hydrogel was synthesized through crosslinking method. Formaldehyde was used as a crosslinking agent. To achieve a hydrogel with high swelling capacity, the resulted hydrogels were saponified using NaOH solution at high temperature. During saponification, ammonia gas i...

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Bibliographic Details
Published in:	Journal of applied polymer science Vol. 109; no. 2; pp. 1083 - 1092
Main Authors:	Marandi, G. Bagheri, Esfandiari, K, Biranvand, F, Babapour, M, Sadeh, S, Mahdavinia, G.R
Format:	Journal Article
Language:	English
Published:	Hoboken Wiley Subscription Services, Inc., A Wiley Company 15-07-2008 Wiley
Subjects:	Applied sciences crosslinking Exact sciences and technology hydrogel Organic polymers pH-sensitivity Physicochemistry of polymers poly(acrylamide) Properties and characterization Solution and gel properties swelling Absorbent material Swelling Crosslinking pH effect Absorptivity Sodium acrylate copolymer Experimental study Property processing relationship Porous material Formaldehyde Saponification Colloidal gel poly(acrylamide) Chemical modification pH- sensitivity Acrylamide copolymer Acrylamide polymer Water absorption Hydrogel
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Summary:	Poly(acrylamide) superabsorbent hydrogel was synthesized through crosslinking method. Formaldehyde was used as a crosslinking agent. To achieve a hydrogel with high swelling capacity, the resulted hydrogels were saponified using NaOH solution at high temperature. During saponification, ammonia gas is produced from hydrolysis reaction of amide groups. The arising of ammonia produces porous structure in hydrogels, which is confirmed using scanning electron microscopy. The conversion of amide groups to carboxylate groups was identified by FTIR spectroscopy. The reaction variables in both crosslinking and hydrolysis reactions that affect the swelling of hydrogels were optimized. The swelling of the hydrogels in various salt solutions with various valencies and radii was studied. Also, the absorbency under load was measured. The hydrogels exhibited pH-sensitivity characteristics. A sharp swelling change was observed in lieu of pH variations in a wide range (1-13). The swelling variations were explained according to the swelling theory based on the hydrogel chemical structure. The pH-reversibility and on-off switching behavior makes the intelligent hydrogels as good candidates for considering as potential drug carries.
Bibliography:	http://dx.doi.org/10.1002/app.28205 istex:BCD0B46DE9E69B7AF3ED9B044E0871EE60B5D567 ark:/67375/WNG-KTZK15CL-8 ArticleID:APP28205 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	0021-8995 1097-4628
DOI:	10.1002/app.28205