Characteristics of Poly(vinyl Alcohol) (PVA) Based Composites Integrated with Green Synthesized Al³⁺-Metal Complex: Structural, Optical, and Localized Density of State Analysis

Abstract

The influence of dispersing Al-metal complex on the optical properties of PVA was investigated using UV–visible spectroscopy. Polymer composite films with various Al3+-complex amounts in the PVA matrix were arranged by solution casting technique by means of distilled water as a widespread solvent. The formation of Al3+-metal complex was verified through Ultraviolet–visible (UV-Vis) and Fourier-transform infrared spectroscopy (FTIR) examinations. The addition of Al-complex into the polymer matrix led to the recovery of the optical parameters such as dielectric constant (εr and εi) and refractive index (n). The variations of real and imaginary parts of complex dielectric constant as a function of photon wavelength were studied to calculate localized charge density values (N/m*), high-frequency dielectric constant, relaxation time, optical mobility, optical resistivity, and plasma angular frequency (ωp) of electrons. In proportion with Al3+-complex content, the N/m* values were amplified from 3.68 × 1055 kg−1 m−3 to 109 × 1055 kg−1 m−3. The study of optical parameters may find applications within optical instrument manufacturing. The optical band gap was determined from Tauc’s equation, and the type of electronic transition was specified. A remarkable drop in the optical band gap was observed. The dispersion of static refractive index (no) of the prepared composites was analyzed using the theoretical Wemple–DiDomenico single oscillator model. The average oscillator energy (Eo) and oscillator dispersion energy (Ed) parameters were estimated.

Keywords

• metal complex
• coordination chemistry
• UV-Vis
• FTIR
• XRD analysis
• optical properties