Water absorbency studies of c-radiation crosslinked poly(acrylamide-co-2,3-dihydroxybutanedioic acid) hydrogels Erdener Karada g a, * , Dursun Saraydin b ,OlgunG€ uven c a Fen-Edebiyat Faculty, Department of Chemistry, Adnan Menderes University, TR-09010 Aydın, Turkey b Department of Chemistry, Cumhuriyet University, TR-58140 Sivas, Turkey c Department of Chemistry, Hacettepe University, Beytepe, 06532 Ankara, Turkey Received 18 March 2004; received in revised form 6 May 2004 Abstract Water absorbency behavior of acrylamide (AAm)/2,3-dihydroxybutanedioic acid (DBA) hydrogels synthesized by c-radiation crosslinking of AAm and DBA in an aqueous solution was investigated. Different amounts of DBA con- taining AAm/DBA hydrogels were obtained in the form of rods via a radiation technique. Swelling experiments were performed in water at 25 °C, gravimetrically. The influence of absorbed dose and DBA content of the hydrogels on swelling properties were examined. The hydrogels showed enormous swelling in an aqueous medium and displayed swelling characteristics which were highly dependent on the chemical composition of the hydrogels and irradiation dose.Diffusionbehaviorandsomeswellingkineticparameterswereinvestigated.Thevaluesoftheweightswellingratio of AAm/DBA hydrogels were between 8.34 and 15.16, while the values of the weight swelling ratio of pure AAm hydrogels were between 7.58 and 8.28. Water diffusion into hydrogels was found to be non-Fickian in character. Equilibrium water contents of the hydrogel systems were changed between 0.8681 and 0.9340. Ó 2004 Elsevier B.V. All rights reserved. Keywords: Acrylamide; 2,3-dihydroxybutanedioic acid; Hydrogel; Gamma radiation; Swelling 1. Introduction Materialswiththeabilitytoabsorbwaterinhigh amounts are again under investigation, because of their potential applications in bioengineering, biomedicine, food industry, communication tech- nology, building industry, chromatography, water purification, separation processes and agriculture. Especially polymers can absorb water up to few hundredtimesoftheirownweight.Thesepolymers areoftencalledwatersuperabsorbentsorpolymer hydrogels. Water super absorbents generally are lowcrosslinkedhydrophilicelectrolytes[1–9]. Hydrogels are often based on water-soluble polymers, in particular, on statistic copolymers of acrylamide with some hydrophilic co-monomers, crosslinkedbychemicalorradiationtechniques.In recent years, it was determined that crosslinked polymericmaterialshavingfunctionalgroupssuch * Corresponding author. Tel.: +90-256-212-8498; fax: +90- 256-213-5379. E-mail address: ekaradag@adu.edu.tr (E. Karada g). 0168-583X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2004.06.010 Nuclear Instruments and Methods in Physics Research B 225 (2004) 489–496 www.elsevier.com/locate/nimb