Polymer Composites with 0.98 Transparencies and Small Optical Energy Band Gap Using a Promising Green Methodology: Structural and Optical Properties

Muaffaq M Nofal; Shujahadeen B Aziz; Jihad M Hadi; Wrya O Karim; Elham M A Dannoun; Ahang M Hussein; Sarkawt A Hussen

doi:10.3390/polym13101648

Polymer Composites with 0.98 Transparencies and Small Optical Energy Band Gap Using a Promising Green Methodology: Structural and Optical Properties

Polymers (Basel). 2021 May 19;13(10):1648. doi: 10.3390/polym13101648.

Authors

Muaffaq M Nofal¹, Shujahadeen B Aziz^{2

3}, Jihad M Hadi⁴, Wrya O Karim⁵, Elham M A Dannoun⁶, Ahang M Hussein², Sarkawt A Hussen²

Affiliations

¹ Department of Mathematics and General Sciences, Prince Sultan University, P.O. Box 66833, Riyadh 11586, Saudi Arabia.
² Hameed Majid Advanced Polymeric Materials Research Laboratory, Physics Department, College of Science, University of Sulaimani, Qlyasan Street, Sulaimani 46001, Kurdistan Regional Government, Iraq.
³ Department of Civil Engineering, College of Engineering, Komar University of Science and Technology, Sulaimani 46001, Kurdistan Regional Government, Iraq.
⁴ Department of Medical Laboratory of Science, College of Health Sciences, University of Human Development, Sulaimani 46001, Kurdistan Regional Government, Iraq.
⁵ Chemistry Department, College of Science, University of Sulaimani, Qlyasan Street, Sulaimani 46001, Kurdistan Regional Government, Iraq.
⁶ Associate Director of General Science Department, Woman Campus, Prince Sultan University, P.O. Box 66833, Riyadh 11586, Saudi Arabia.

Abstract

In this work, a green approach was implemented to prepare polymer composites using polyvinyl alcohol polymer and the extract of black tea leaves (polyphenols) in a complex form with Co²⁺ ions. A range of techniques was used to characterize the Co²⁺ complex and polymer composite, such as Ultraviolet-visible (UV-Visible) spectroscopy, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The optical parameters of absorption edge, refractive index (n), dielectric properties including real and imaginary parts (ε_r, and ε_i) were also investigated. The FRIR and XRD spectra were used to examine the compatibility between the PVA polymer and Co²⁺-polyphenol complex. The extent of interaction was evidenced from the shifts and change in the intensity of the peaks. The relatively wide amorphous phase in PVA polymer increased upon insertion of the Co²⁺-polyphenol complex. The amorphous character of the Co²⁺ complex was emphasized with the appearance of a hump in the XRD pattern. From UV-Visible spectroscopy, the optical properties, such as absorption edge, refractive index (n), (ε_r), (ε_i), and bandgap energy (E_g) of parent PVA and composite films were specified. The E_g of PVA was lowered from 5.8 to 1.82 eV upon addition of 45 mL of Co²⁺-polyphenol complex. The N/m* was calculated from the optical dielectric function. Ultimately, various types of electronic transitions within the polymer composites were specified using Tauc's method. The direct bandgap (DBG) treatment of polymer composites with a developed amorphous phase is fundamental for commercialization in optoelectronic devices.

Keywords: UV-vis study; XRD and FTIR; bandgap study; localized density of state; metal complex; small bandgap PVA composites.