Impact of natural melanin doping on the structural, optical and dielectric characteristics of the PVP/CMC blend

Abstract

Undoped and doped polyvinyl pyrrolidone/ carboxymethyl cellulose (PVP/CMC: 50/50%) blended polymers with melanin were formed. X-ray diffraction analysis confirmed the amorphous nature of all blends. Scanning electron microscopy results confirmed the smooth and homogeneous surface of the undoped and doped PVP/CMC blend with melanin. The optical parameters and fluorescence spectra of the PVP/CMC blend were investigated as functions of melanin content. The direct optical band gap (Eg) for the used melanin is 2.86 eV. The direct and indirect Eg values for the PVP/CMC blend are 5.1 and (4.9, 3.2) eV, respectively. The direct and indirect Eg values were reduced to (4.5, 3.23) and (2.2, 1.33) eV as the amount of melanin became 3 wt % in the doped blend. The effect of melanin doping on the dielectric constant, dielectric loss, AC conductivity, complex impedance, Nyquist plot of the complex impedance, and electric modulus of the PVP/CMC blend was also studied.

Keywords

• PVP/CMC
• Melanin
• optical
• dielectric