The effect of charge density and conformation on the polyelectrolyte complex formation between carrageenan and chitosan

The formation of polyelectrolyte complexes (PECs) between chitosan varying in degree of deacetylation (DD) and kappa-, l- and lambda-carrageenan, respectively, was investigated, in moderately concentrated solutions, with emphasis on the effect of charge density and conformation. Results obtained indicate that macroscopically electroneutral PECs were formed when chitosan interacted with carrageenan molecules in coil or non-aggregated helical conformation. When the kappa-carrageenan existed in an aggregated helical conformation the interaction with chitosan produced PECs with a charge ratio of chitosan to carrageenan below unity. Furthermore, the PEC formation process proved to be significantly affected by the presence of low molecular weight polyelectrolyte components. (C) 1997 Elsevier Science Ltd.