APPLICATION OF FTIR IN THE DETERMINATION OF ACRYLATE CONTENT IN POLY(SODIUM ACRYLATE-CO-ACRYLAMIDE) SUPERABSORBENT HYDROGELS

Hydrogels have been prepared by free-radical solution copolymerization of acrylamide and sodium acrylate (NaAc), with molar ratio ranging from 25/75 to 80/20, respectively, using methylene bisacrylamide as the crosslinking agent. A FTIR spectroscopy procedure to determine the acrylate/acrylamide ratio in these hydrogels was proposed based on absorbance at 1410 cm(-1) (nu COO-) and 2940 cm(-1) (nu CH and nu CH2). A straight line with a good linear correlation coefficient (0.998) was obtained by plotting the acrylate content (Ac%) versus relative absorbance (A(rel) = A(1410)/A(2940)). Results were confirmed by the amount of sodium cation released in acid medium determined by atomic absorption spectrometry.