Multifunctional chitosan/montmorillonite/TiO2 nanocomposites: Correlating microstructure with dielectric and photocatalytic properties

Abstract

A blend of polymer, clay, and metallic oxide is used to improve the inherent properties of hybrid nanocomposites (NCs). This work investigate the functional/microstructural characteristics of synthesized NCs made of TiO₂ nanoparticles (NPs), chitosan (CTS), and Na-montmorillonite (MMT). Solution blending is used to carry out the synthesis process. The correlation of results from analytical techniques, including as X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), Impedance Spectroscopy (IS), and UV-VIS spectrophotometry, ensures the analysis accuracy. Microstructural analysis confirms successful NC synthesis, irrespective of initial stoichiometry. Semiquantitative XRD analysis reveals intensity and sharpness variations in specific reflections, indicating effective synthesis. Stoichiometric variations induce structural aberrations, manifesting as shifts in XRD reflection positions and intensity fluctuations. TEM/EDX studies demonstrate that increased clayey fraction abundance facilitates the intercalation process and exfoliation of organic-enclosing "clay-particles”. Energy Dispersive X-ray Spectroscopy (EDS) mapping confirmed the successful NCs synthesis, revealing a homogeneous distribution of montmorillonite, chitosan, and TiO₂ nanoparticles with strong chemical compatibility between the components, despite a slight agglomeration of TiO₂ nanoparticles. FTIR spectroscopy reveals characteristic absorption bands of the polymer fraction, persisting across various initial synthesis ratios. This phenomenon is attributed to CTS surface modification, inducing oscillations in TiO₂ NPs' bandgap energy. IS analysis indicates that the synthesized NCs exhibit semiconductor-like behaviour and demonstrate dispersive characteristics with frequency-dependent power loss as dielectric materials. The photocatalytic efficacy of the nanocomposites was evaluated through Rhodamine B degradation experiments, revealing significant performance across samples. The analysis demonstrated a remarkable degradation of Rhodamine B achieving 98.3 % concentration reduction. The consistent appearance of the main peak around 5 min and the presence of additional peaks indicating degradation products confirm the efficient photocatalytic breakdown of the compound. These findings underscore the relationship between synthesis parameters, structural modifications, and functional properties.