Effect of gamma radiation on the structure, electrical, optical, and dielectric properties of PVDF-PMMA/MCTBO nanocomposites for electrochemical and optical applications

• Nanocomposites samples of PVDF-PMMA/MCTBO were successfully prepared by casting method. • How can these PVDF-PMMA/MCTBO nanocomposite be fine-tuned to have diverse optical, dielectric, and electrical properties? • The dielectric and optical properties of the PVDF-PMMA/MCTBO samples are improved. • The PVDF-PMMA/MCTBO samples were suggested to be used in energy storage systems, and radiation shielding materials. Polymer nanocomposites (PNC) based on polymethyl methacrylate (PMMA) and polyvinylidene fluoride (PVDF) were synthesized by the casting technique, incorporating different weight percentages of multi-walled carbon nanotubes and Bismuth oxide nanoparticles (MCTBO NP). The prepared films were subjected to 100 kGy of gamma irradiation to investigate structural and functional modifications. X-ray diffraction (XRD) analysis revealed that doping with MCTBO led to a notable increase in the amorphous phase and a corresponding decrease in crystallinity. This structural transition was further supported by an increase in Urbach energy from 0.175 eV to 3.25 eV, particularly after irradiation, indicating enhanced structural disorder. Scanning electron microscopy (SEM) confirmed the uniform dispersion of nanoparticles throughout the polymer matrix, verifying successful integration of nanofillers. Optical characterization demonstrated a significant reduction in the optical band gap (indirect), which decreased from 3.87 eV to 3.18 eV upon MCTBO doping, and further to 2.36 eV after irradiation. This reduction is attributed to increased cross-linking and the introduction of localized states resulting from radiation exposure. Tauc’s plots indicated that the optical transitions in both irradiated and non-irradiated samples are of the indirect type. Moreover, the Urbach energy increased with both higher MCTBO content and gamma irradiation, reflecting greater electronic disorder. Additionally, electrical conductivity and dielectric properties were evaluated before and after irradiation. Results demonstrated enhanced dielectric constant and electrical conductivity with increasing MCTBO concentration and post-irradiation, suggesting improved charge transport characteristics. Among all samples, the PMMA/PVDF nanocomposite containing 6 wt% MCTBO exhibited the most superior performance, surpassing both the pristine blend and its non-irradiated counterpart. The enhanced structural, optical, and electrical properties highlight the potential of these irradiated nanocomposites for advanced applications in optoelectronic devices, energy storage systems, and radiation shielding materials.