Structure and Properties of Chitosan-silver Nanoparticles Nanocomposites

Chitosan-silver nanoparticles (CS-AgNP’s) composite films have been synthesized by three different methods. Structure and relaxation properties of nanocomposites films have been analyzed by scanning electron microscopy, thermo-gravimetry analysis, infrared, dielectric spectroscopy and X-ray photoelectron spectroscopies. Two relaxation processes have been detected; in the wet films in the temperature range 25-70°C (with water content between 1-11 wt%, TGA measurements) the α-relaxation associated with the glass-rubber transition has been observed. The second relaxation was observed in the temperature range 80-160°C and it has been identified as the σ-relaxation which is often associated with the hopping motion of ions in the disordered structure of the composite. These relaxation processes and DC conductivity depend upon the method of preparation and concentration of AgNP’s. Based upon the results, a possible mechanism of interaction between AgNP’s and chitosan matrix and the influence of nanoparticles concentration on structure, relaxation and electrical properties have been proposed.