Effect of TiO2 nanoparticles on the structural configurations and thermal, mechanical, and optical properties of chitosan/TiO2 nanoparticle composites

Abstract

The solution casting method was used to prepare nanocomposite films of chitosan/TiO2 nanoparticles (NPs) because of their applications in various fields. The effects of TiO2NP concentration on the structural, morphological, thermal, mechanical, and optical properties of such films were studied by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, and thermal analysis (thermogravimetric analysis [TGA] and differential scanning calorimetry [DSC]). The XRD patterns reveal miscibility between the amorphous components of chitosan and TiO2NPs. The HRTEM and FESEM images illustrate the distribution and dispersion of TiO2NPs on the film surface. Data from FTIR spectroscopy, DSC, and TGA and the mechanical properties indicate the dependence of chitosan properties on the presence of TiO2NPs and the existence of interactions between chitosan and TiO2NPs. The reflectance and transmittance values obtained were used to calculate the CIE tristimulus values, color parameters, refractive index, absorption coefficient, dielectric spectra, optical conductivity, volume energy loss function (VELF), and surface energy loss function (SELF). The dependence of the absorption coefficient on the photon energy demonstrated that the optical transfer is permissible and direct. The variations of the dielectric spectra and optical conductivity indicate different interactions between photons and electrons in the films produced and relate to the electronic structure. The values of the VELF were found to be greater than those of the SELF, which confirms that the energy loss occurred mostly within the material. Films were also examined for water vapor transmission (WVT) and water vapor permeability (WVP), and the results showed that incorporation of TiO2NPs onto chitosan caused a decrease of WVT and WVP. In addition, the antimicrobial activity of the nanocomposite films against Gram-positive and Gram-negative bacteria was studied, and good antimicrobial activity was found, indicating their ability to inhibit bacterial proliferation at the culture site. The developed chitosan thin films supporting an optimized amount of TiO2NPs could be used to treat various diseases.