POLYELECTROLYTE COMPLEXES OBTAINED BY RADICAL POLYMERIZATION IN THE PRESENCE OF CHITOSAN

The radical polymerization of acrylic acid and sodium 4-styrenesulfona te in the presence of chitosan as a template gives insoluble products, identified as the polyelectrolyte complexes chitosan-poly(acrylic aci d) and chitosan-poly(4-styrenesulfonate). Kinetic results do not permi t to propose any mechanism in the first case, while suggest a ''pickup '' one in the second. The polyelectrolyte complexes have been characte rized by FT-IR spectroscopy, X-ray diffractometry, optical and scannin g electron microscopies, differential scanning calorimetry and thermog ravimetric analysis. The results obtained indicate an ordered structur e for the first complex, while the second one appears similar to that obtained by reacting the parent polymers. Therefore, the template poly merization technique appears advantageous only for the synthesis of th e chitosan-poly(acrylic acid) complex. The thermal analysis shows that the complexes undergo two successive modifications on heating. FT-IR analysis demonstrates that the first process is an esterification betw een the hydroxyls of chitosan and the acidic groups of both daughter p olymers; the second one appears to be an amidation of the chitosan amm onium groups only with the sulfonate groups.