Green synthesized Al-metal complex to reduce the crystalline phase and improve the optical properties of CS based polymer blends

Abstract

In the present study, a green coordination chemistry technique is used for the preparation of Aluminum complexes (Al3+-polyphenol complex) by using black tea extract solution. Chitosan: Poly(2-ethyl-2-oxazoline) (CS: POZ) composite samples loaded with Al3+-complex was arranged by solution casting technique. Various techniques were used to characterize the films, such as UV–Visible spectroscopy, fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). The shifting of the peaks and their reduction in intensity in both XRD and FTIR confirmed the amorphous development with the loading of the Al3+-complex and the production of strong interaction between functional groups of the CS: POZ with the Al3+-complex, respectively. The insertion of the Al3+-complex into the host polymer matrix resulted in the creation of a polymer composite with controlled optical properties and improved optical parameters, including dielectric constant (εr), dielectric loss (εi) and refractive index (n). The complex dielectric constant's real and imaginary components as a function of photon wavelength were explored to derive various high-frequency characteristics. This includes extracting dielectric constant at short wavelength (ε∞), optical resistivity (ρopt), localized charge density values (N/m*), plasma angular frequency (ωp), optical mobility (μopt), and relaxation time (τ) of electrons, in which all these optical parameters are important for choosing suitable materials for optoelectronic applications. In accordance with (45 ml of Al3+-complex insertion), both ωpandN/m* magnitudes are enlarged up to 10-times, while the optical band gap is remarkably dropped (4.8–1.65 eV), which is calculated using Tauc's relation, and the electronic transition mode was identified by using optical dielectric loss (εi). Moreover, the Wemple–DiDomenico single oscillator model was applied to study the dispersion behavior of their refractive index and estimate the oscillator dispersion energy (Ed) and average oscillator energy (Eo) and parameters. The polymer composite with absorption performance in the visible region and other superior optical properties is fundamental for photo cells and commercialization in optoelectronic devices.