Preparation of superabsorbent polymers by crosslinking acrylic acid and acrylamide copolymers

Abstract

High water-absorbent copolymers comprising acrylic acid (AA) and acrylamide (AM) were prepared in the presence of a crosslinking agent, monofunctional aldehyde, by a solution polymerization technique using a redox initiation system. Such copolymers have very high water absorbency and absorbing kinetics to the distilled water. The copolymer formed which absorbed about 900 g water/g dry copolymer was used to study the influence of sodium chloride on the absorption capacity at 24ЊC. The swelling of this copolymer was studied in alcohol/water mixtures of increasing alcohol content at 294, 304, and 314 K. The main transition for ethanol/water and methanol/ water mixtures is a rapid decrease of the retention capacity of the copolymer at 50-60 vol % ethanol and 55-65 vol % methanol, respectively. Swelling in distilled water at different temperatures ( T ) and the effect of solvent composition were also studied. Among the variables examined were initiator concentration, polymerization temperature, and amount of AM in the copolymer.

Synthesis of poly(acrylamide-co-acrylic acid)-based super-absorbent hydrogels by gamma radiation: study of swelling behaviour and network parameters

“…When AAm content was increased during the polymerization from 43.14% to 47.70%, then there was a slight decrease in equilibrium water absorbency of the hydrogels (i.e., from 829 to 801 g water/g sample). This slight decrease in water absorbency may be result of increase in soluble materials at a fixed radiation dose [18]. This can be supported by weighing dried 43.14% and 47.70% AAm hydrogels, after the equilibrium absorption state.…”

“…Karadag et al [17] prepared highly-swollen AAm/crotonic acid hydrogels (in the rod form) containing some inorganic salts such as ammonium nitrate, potassium nitrate and ammonium sulphate used as fertilizer, an agricultural drug, such as ethylene glycol dimethacrylate, and 1,4-butandiol dimethacrylate by co-polymerization of AAm and crotonic acid with gamma radiation. Lui and Rempel [18] prepared high-water-absorbent copolymers based on AAc and AAm by solution polymerization. The AAm content was varied from 1.0 to 5.0% of the total monomer to synthesize the super-absorbent polymers.…”

Synthesis, Characterization and Swelling Properties of Chitosan/Poly(acrylic acid-co-crotonic acid) Semi-Interpenetrating Polymer Networks

“…Many researchers have investigated the crosslinking of chitosan via aldehyde functional group containing reagents. 14,16 As seen in Scheme 1(b), at the first step, the imine bond formation takes place between amine group of chitosan and formyl group of GA. Then the second imine group is formed with the amine group of other chitosan chain and the crosslinks formed result in the semi-IPN hydrogel in the presence of poly(AA-co-CA) (Scheme 1(c)). Structural Characterization.…”

Effect of calcium neutralization on elastic and swelling properties of crosslinked poly(acrylic acid) - correlation to inhomogeneities and phase behaviour

“…They can be used in pharmacy as drug delivery systems, in hygiene products as absorbents, in biotech as ion-exchange resins, in engineering as self repairing seals, among other applications [1][2][3]. Poly(acrylic acid) (PAA) is commonly used to form hydrogels because acrylic acid is cheap and easy to polymerize into high molecular weight compounds and because of its ability to absorb many times its own weight of water [1,4].…”