Dielectric and mechanical performance of barium titanate (BT) and copper oxide (CuO) reinforced polyvinyl alcohol (PVA) nanofibers for flexible microelectronic applications

Polyvinyl alcohol (PVA)-based nanofibers were reinforced with copper oxide (CuO) and barium titanate (BaTiO₃, BT) to form ternary composite nanofibers via electrospinning, targeting improvements in dielectric and mechanical properties for potential microelectronic and energy-related applications. Composite solutions with 5, 10, and 15 wt.% of combined CuO-BT fillers were prepared and electrospun into nanofibers. Structural and morphological characterizations were carried out using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). XRD analysis confirmed the semi-crystalline nature of PVA, and a decrease in crystallinity of PVA with filler incorporation. SEM micrographs showed smooth, continuous fibers at lower filler content, while higher loadings induced agglomeration. Dielectric measurements performed using an LCR meter revealed that the 10 wt.% CuO-BT/PVA composite exhibited the highest dielectric constant (∼23.4), capacitance (148 pF), and AC conductivity (1.1 × 10^-7 S/m), while further increases in filler content led to a decline, indicating optimal composition. Dielectric losses (tan δ) increased with filler loading, suggesting trade-offs between conductivity and energy dissipation. Mechanical testing using a universal testing machine (UTM) showed a substantial increase in Young’s modulus from 0.24 GPa (pure PVA) to 6.67 GPa at 5 wt.%, followed by a reduction at higher filler contents due to filler agglomeration and interfacial defects. The optimized 10 wt.% composite nanofibers demonstrated enhanced performance, making CuO and BT co-doped PVA nanofibers promising candidates for dielectric layers in flexible electronics and capacitive components.