Modulating structural, dielectrical and optical properties of PVA/methylcellulose/WO₃ nanocomposites for energy storage and optoelectronics applications

Abstract

In this study, different polyvinyl alcohol (PVA)/methylcellulose/WO3 nanocomposites with composition of xPVA‐(100‐x) Methylcellulose (MC)‐2WO3 (where x = 100, 80, 60, 40, 20, and 0 wt%) were prepared successfully by solution casting technique. WO3 nanoparticles were introduced with 2 wt% to enhance the dielectric performance of the PVA/MC blend. The effect of changing PVA/MC weight ratios inside the nanocomposites on the structural, optical, and dielectric properties were studied by X‐ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), UV–VIS, and dielectric relaxation spectroscopy. The intensity of the PVA peak was altered randomly with varying MC ratios in the nanocomposites, which indicated disruption of the crystalline phase of PVA. Among nanocomposites, 20PVA‐80MC‐2WO3 showed the highest electrical conductivity, highest dielectric constant, longest relaxation time, and the lowest optical energy band gap due to the increased amorphous phase and disorders. In contrast, 60PVA‐40MC‐2WO3 exhibits the lowest dielectric constant and lowest conductivity, because of its high crystallinity. The decrease in the real part of impedance (Z′) value was seen in samples containing both PVA and MC polymers compared with that containing one polymer species, which attributed to the rise in the proportion of amorphous regions, leading to increased mobility of the polymer chains. Nyquist plots of nanocomposites showed angled spike and semicircle combinations, which are the typical characteristics of ionic conducting materials. Our results show that nanocomposites' PVA/MC ratio may be adjusted for many applications like energy storage, radiofrequency, and optoelectronics.