Modification of structural and linear/nonlinear optical properties of multifunctional PVC/MgO nanocomposites for UV shielding and photonics applications

Here, the PVC/MgO nanocomposite films containing 1, 2, and, 3 wt. % MgO were prepared using the casting solution technique. EDX and Elemental mapping analyses confirm the successful MgO incorporation inside PVC without impurities. EDX, elemental mapping, and FTIR analyses confirmed the successful incorporation of MgO nanoparticles into the PVC matrix without impurities, while preserving the polymer chemical structure. SEM/TEM results also revealed well-dispersed MgO nanoparticles (17–30 nm) within the PVC matrix, with increasing surface roughness and slight agglomeration observed at higher loadings. The optical studies show that MgO incorporation significantly enhances the absorbance and reduces the reflectance in PVC films. Tauc analysis demonstrated that adding 3 wt% MgO reduced the direct and indirect optical band gaps of PVC from 5.88 to 5.62 eV to 4.98 and 4.57 eV, respectively, accompanied by an increase in Urbach energy. Moreover, the incorporation of 3 wt% MgO nanoparticles increased the extinction coefficient and optical conductivity (from 1.23 × 10¹¹ to 6.12 × 10¹¹ s/cm²), while reducing the refractive index from 1.41 to 1.20 at approximately 300 nm. The real and imaginary dielectric constant analyses reveal that MgO incorporation decreases ε_r, whereas ε_i, VELF, and SELF exhibit increasing trends. The dispersion, oscillation energy, and relaxation time (E_d, E_o, and τ) were estimated to be 3.12, 6.08, and 0.88 ×10⁻⁵ sec for the PVC film, which decreased to 2.13, 5.71, and 0.73 × 10⁻⁵ sec after insertion 3% MgO, respectively. Nonlinear optical parameters, including χ⁽¹⁾, χ⁽³⁾, and n₂ decreased with MgO incorporation due to reducing the electronic polarizability. These findings confirm that MgO incorporation effectively tunes the optical and nonlinear properties of PVC nanocomposites, making them highly promising for advanced photonic and UV-shielding applications.