Preparation and NMR characterization of superporous hydrogels (SPH) and SPH composites

In this investigation the mechanism of synthesis and characterization of Superporous Hydrogel (SPH) and SPH composites were studied. Solid-state C-13 NMR was used for elucidating the structure of the polymers. Scanning electron microscopy (SEM), apparent density and swelling ratio studies were used to characterize these polymers. The results showed the SPH polymer was made of the sequence of acrylamide and acrylic acid monomers as a backbone chain, which was cross-linked with N,N'-methylenebis acrylamide. Sodium bicarbonate added in the last step of the synthesis was used to generate CO2 formation, causing a large number of interconnecting pores within the polymer structure. SPH composite polymers were made in the same way, except for changing the amount of monomers and using Ac-Di-Sol as a stabilizer. The cellulosic fibres of Ac-Di-Sol will overlap the backbone chain, so the mechanical stability of these polymers will be increased. Characterization of the prepared polymers by SEM, measurement of the apparent density together with swelling ratio studies showed that SPH polymers have more pores and higher swelling ratio but less mechanical stability compared to SPH composite polymers, which have less pores and lower swelling ratio but a higher mechanical stability. (C) 2000 Elsevier Science Ltd. All rights reserved.