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

In this investigation the mechanism of synthesis and characterization of Su perporous Hydrogel (SPH) and SPH composites were studied. Solid-state C-13 NMR was used for elucidating the structure of the polymers. Scanning electr on 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 chai n, which was cross-linked with N,N'-methylenebis acrylamide. Sodium bicarbo nate added in the last step of the synthesis was used to generate CO2 forma tion, causing a large number of interconnecting pores within the polymer st ructure. SPH composite polymers were made in the same way, except for chang ing the amount of monomers and using Ac-Di-Sol as a stabilizer. The cellulo sic fibres of Ac-Di-Sol will overlap the backbone chain, so the mechanical stability of these polymers will be increased. Characterization of the prep ared polymers by SEM, measurement of the apparent density together with swe lling ratio studies showed that SPH polymers have more pores and higher swe lling ratio but less mechanical stability compared to SPH composite polymer s, which have less pores and lower swelling ratio but a higher mechanical s tability. (C) 2000 Elsevier Science Ltd. All rights reserved.