Effect of cupric ion on thermal degradation of quaternized chitosan

The thermal degradation of quaternized chitosan-cupric ion compounds in nitrogen was studied by thermogravimetry analysis (TG) and differential thermal analysis (DTA). The effect of cupric ions on the thermal degradation behaviors of quaternized chitosan was discussed. Fourier transform-infrared (FTIR) and X-ray diffraction (XRD) were utilized to determine the micro-structure of quaternized chitosan-cupric ion compounds. The results of FTIR and XRD show that there are coordinating bonds between quaternized chitosan and cupric ions. Thermal analysis indicates that the thermal degradation of quaternary chitosan-cupric ion compounds is a two-stage reaction, in which there are the decomposition of N-C2 bond on the side-chain of quaternized chitosan and the cleavage of glycosidic linkages of chitosan. The two reactions are exothermic. The impact of cupric ion on the thermal degradation of quaternized chitosan is significant, and the temperature and activation energy of the degradation are related to the weight fraction of the cupric ion.