Interaction of chitosan with natural or synthetic anionic polyelectrolytes. 1. The chitosan–carboxymethylcellulose complex

Chitosan, the unique cationic groups-containing polysaccharide is a natural, renewable, nontoxic and biodegradable source being considered as ‘ecologically-friendly’ product. It has been studied as partner in several intermacromolecular complexes (IMC) with natural or synthetic anionic polyelectrolytes. The present investigation discusses some new results on the chitosan–carboxymethylcellulose interaction studied in solution by conductometric, potentiometric and turbidimetric titration, and in the solid phase by FTIR spectra or thermogravimetric analysis. All the titration methods confirmed the formation of complexes in a stoichiometric ratio between partners. Analysis of the solid phase complex by FTIR spectra evidenced some bands characteristic of the electrostatic interaction, along with other bands, suggesting the partial recovery of the NH2 and COOH groups. The difference between the behavior of single partner, complex and physical mixture was clearly evidenced by differential thermal analysis. The mechanism of thermal degradation in air is quite complex.