Semi-IPNs of starch and poly(acrylamide-co-sodium methacrylate): Preparation, swelling and diffusion characteristics evaluation

Abstract

Semi-interpenetrating polymer network (IPN) hydrogels composed of starch and random copolymer of poly(acrylamide-co-sodium methacrylate) [poly(AAm-co-NMA)] were prepared by polymerizing an aqueous solution of acrylamide (AAm), sodium methacrylate (NMA) using ammonium persulphate (APS)/ N, N, N 1, N 1-tetramethylethylenediamine (TMEDA) as redox initiating system in presence of a crosslinker and starch solution. IR spectroscopy was used to identify the presence of different repeating units in the IPN networks. The swelling and diffusion characteristics, such as initial swelling rate ( r i), swelling rate constant ( k s), equilibrium swelling ratio ( S eq), diffusion constant ( n) and diffusion coefficients ( D) were evaluated for different semi-IPN hydrogels prepared under various formulations. For better understanding of network structure formation of these semi-IPNs, three different crosslinkers namely, N, N-methylenebisacrylamide (MBA), 1,4-butanediol diacrylate (BDDA) and diallyl phthalate (DP) were employed. Further, the swelling pattern of semi-IPN hydrogels was studied in different physiological, pH and ionic/salt solutions and showed great responsiveness due to their ionic character. The morphological features of these IPNs were observed using scanning electron microscopy (SEM).