Eco-benign Fabrication of PVA/CuO Nanocomposites: Phase purity, interfacial microstrain, and optical/dielectric enhancement

Abstract
Copper-oxide/poly (vinyl alcohol) (PVA) nanocomposite films were prepared by a fully aqueous, green route that combines green-tea-assisted synthesis of CuO nanoparticles with solution casting. Free-standing PVA/CuO membranes containing 0–6 wt % filler (PVACu0–PVACu6) formed uniform, transparent films. FESEM revealed well-dispersed CuO domains with nanoscale morphology, and EDS confirmed the expected Cu and O signals and the low-level filler composition in the polymer matrix. X-ray diffraction verified tenorite CuO and the characteristic PVA halo, while peak broadening indicated nanoscale oxide domains and polymer-confinement microstrain. FTIR showed load-dependent changes in O–H and C–O vibrations, evidencing interfacial hydrogen bonding between PVA chains and CuO surfaces. UV–visible spectroscopy demonstrated enhanced near-UV attenuation with increasing CuO content, a slight red-shift of the absorption edge, and a corresponding reduction in the Tauc optical band gap (direct and indirect models). Wemple–DiDomenico analysis indicated increasing refractive index and dielectric constants, and a modest rise in Urbach energy pointed to interfacial disorder. These findings show that small CuO additions (≤6 wt %) enable controlled tuning of dispersion, band-edge position, and dielectric response while maintaining film integrity, highlighting these green-processed nanocomposites as promising candidates for transparent UV-blocking coatings and other optoelectronic applications.

Author
Rzgar farooq Rashid

DOI
https://doi.org/10.1016/j.jpcs.2025.113282

ISSN

Publish Date: 19-Oct-2025