Determination of swelling behavior and morphological properties of poly(acrylamide‐co‐itaconic acid) and poly(acrylic acid‐co‐itaconic acid) copolymeric hydrogels

Abstract

Poly(acrylamide-co-itaconic acid) (PAAmIA) and poly(acrylic acid-co-itaconic acid) (PAAIA) copolymeric hydrogels were prepared with different compositions via free-radical polymerization. Ethylene glycol dimethacrylate (EGDMA) was used as an original crosslinker for these monomers. Gelation percentages of the monomers were studied in detail and it was found that addition of IA into the monomer mixture decreased the gelation percentage. The variation in swelling values (%) with time, temperature, and pH was determined for all hydrogels. PAA, which is the most swollen hydrogel, has the swelling percentage value of 2000% at pH ¼ 7.4, 378C. Swelling behaviors were explained with detailed SEM micrographs, which show the morphologic differences between dry and swollen hydrogels.

Pantoprazole-Na Release from Poly(acrylamide-co-crotonic acid) and Poly(acrylic acid-co-crotonic acid) Hydrogels

“…The dissociation constants for AA and CA are pK a ¼ 4.25 and pKa ¼ 4.65, respectively. Since the dissociation constants are very close to each other, the consecutive swellings at these pH values overlap and only single-step swelling versus pH curves are observed [19,34]. As the swelling values of PAA and PAACA hydrogels exhibit greater differences between pH ¼ 2.0 and 8.0, these hydrogels are more sensitive to the variations in pH in this range [18,21,35].…”

“…where M ae is the weight of the dried hydrogel after extraction and M be is the weight of the dried hydrogel before extraction [19]. All measurements were performed in triplicate.…”

“…The gel formation percentages of the discs were gravimetrically determined as follows [19]; the dried hydrogel discs were weighed and then placed in distilled water for 48 h to extract the unreacted monomers. The discs were then taken from the extraction medium and dried in a vacuum oven at 408C to constant weight.…”

Fluconazole release through semi‐interpenetrating polymer network hydrogels based on chitosan, acrylic acid, and citraconic acid

“…42 As the swelling values of all hydrogels exhibit great differences between pH 4.0 and pH 8.0, it is thought that these hydrogels are sensitive to variations in the pH in this range. 12,18,42 SEM analysis SEM micrographs of dry, swollen, and fluconazoleentrapped hydrogels are presented in Figure 5. The appearance of the dry and fluconazole-entrapped hydrogels is similar.…”

“…There are numerous studies about preparing anionic hydrogels with AA in the literature. 12 Besides many studies about poly(acrylic acid) (PAA) hydrogels, some investigations have focused on copolymeric hydrogels containing different vinyl monomers, such as hydroxyethyl methacrylate, N-isopropylacrylamide, crotonic acid, itaconic acid, and acrylonitrile. 13 Citraconic acid (CA) is known as a suitable monomer for radical copolymerization with vinyl monomers.…”