Characterization of selenium oxide nanofiller effect on the spectroscopic and thermal properties of Cs/PAM nanocomposites

Abstract

Nanocomposite samples of chitosan (Cs)/polyacrylamide (PAM) blend incorporated with different concentrations of selenium oxide (SeO2) nanoparticles were fabricated and investigated. The results of Cs/PAM-SeO2 nanocomposites show an exchange in the physical and thermal properties. The X-ray diffraction shows the semicrystalline nature for pure Cs/PAM blend which decreased with the increase of Se contents, causing a decrease of the degree of crystallinity inside Cs/PAM films. The absence of Se peaks for doped films indicates that Se was finely dispersed in polymeric matrices. The FT-IR spectra display a change in the intensities of some bands compared with the spectrum of the virgin Cs/PAM, which indicates that an interaction and complexation between Cs/PAM and selenium nanoparticles took place. The UV–vis measurements revealed that the values of the direct and forbidden direct optical energy gap (Egd and Egf) decreased after the addition of Se nanoparticles. The TG, DTG and DSC analysis were used to investigate the thermal properties of the nanocomposites. The TG thermograms show two regions at ≈ 100 °C varied from 2.8 to 4.6 % weight loss due to the evaporation of water and moisture absorbed, and the other from 244 to 433 °C related to ≈9.5% to ≈55.2 % weight loss. The shifts of TG curves result in a higher temperature indicating that, with the addition of Se, the thermal stability increases with increasing Se content. The values of the change of activation entropy (ΔS*), change of activation enthalpy (ΔH*), and Gibbs free activation function (ΔG*) were calculated. The small increase of both ΔH* and ΔG* reveals that the total energy was increased with respect to the reagents and compound formation activated.