Carrageenan:chitosan polyelectrolyte complexes (PEC) were obtained and the initial components ratio effect on their formation was studied by dynamic light scattering (DLS), atomic force microscopy (AFM) and electrokinetic measurements. It was shown that the PEC formation mechanism is determined by polymer abundance. Positively charged PEC particles (the average value of ζ-potential was 40 mV) stabilized by chitosan amino groups were formed provided that polycation was present in excess in the complex. According to the AFM data, chitosan was located on the carrageenan fibers surface. In PEC where carrageenan prevails the number of unbound sulfate groups decreases if the chitosan content increases. It results in PEC negative surface charge decrease (from -92.4 to -55.6 mV). In this case AFM data showed that chitosan is incorporated into the network structure of carrageenan and at the ratio carrageenan:chitosan 1:0.5 w/w breaks. These data are correlated with the PEC surface charge values and sizes.
polyelectrolyte complex, carrageenan, chitosan, atomic force microscopy, ζ-potential
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