[Spectroscopic investigations on sol-gel transition of alginate solutions by addition of cupric ion]

Viscosity measurements and 13C-NMR, UV/VIS, and Raman spectroscopic studies have been carried out of various concentration of alginate solutions undergoing sol-gel transition induced by addition of cupric cation. From analyses of the spectra, a qualitative explaination was suggested of the interaction mode of the coordination between functional groups and cupric ions, the conformational change of polychains and the behaviour of solvent molecules druing the process of sol-gel transition. The mechanisms of phase transition of our system induced by the heavy metal ion have been discussed.