Rheological properties and fractal structure of concentrated polyion complexes of chitosan and alginate

Rheological properties and fractal structure of the polyion complex between chitosan and alginate have been studied using IR spectra, dynamic viscoelasticity and SAXS measurements. The complexation seems to occur between a carboxyl anion of the alginate and an amino group of the chitosan. The complex develops most markedly at a mixing ratio in weight of the chitosan/alginate from ca. 1/1 to 1/2 (in molar ratio), at which the dynamic viscoelastic functions of the systems manifest a plateau region due to a heterogeneous structure at a low frequency range. The heterogeneous structure shows a surface fractal structure having a fractal dimension of ca. 2.4.