A study on copolymeric hydrogels based on acrylamide-methacrylate and its modified vinyl-amine-containing derivative

Acrylamide-co-methyl methylacrylate (AAm-co-MMA) copolymeric hydrogels of different ratios were prepared by using chemical and physical crosslinks. The physically crosslinked hydrogels were prepared by solution polymerization using benzoyl peroxide as an initiator, while the chemically crosslinked hydrogels were prepared by using N,N'-methylene bisacrylamide (N,N'-MBA) as crosslinking agent. This copolymeric hydrogel was further modified by Hofmann degradation to improve its swelling behaviour. 1 H-nuclear magnetic resonance (H-1-NMR), Fourier transform infra-red spectroscopy (FT-IR), differential scanning calorimetry (DSC) and elemental analysis have been used to characterize the copolymeric gel. Elemental analysis has been used to evaluate the copolymer composition. The influence of environmental conditions such as temperature and pH value on the swelling behaviour of these copolymeric gels was investigated. Results showed that the hydrogels exhibited different equilibrium swelling ratios at different pH and temperature of swelling medium. The temperature and pH sensitivities of these gels also depended on the AAm content in the copolymeric hydrogels. These hydrogels exhibited 2135% swelling at 60degreesC, which was reversible and very good dimensional stability was mentioned. This was due to hydrolysis of amide groups could be hydrolyzed to form negatively charged carboxylate ion in hydrogels in response to an external pH and temperature variation.