Ultraviolet Radiation Driven Multifunctional Polyvinyl Alcohol Based Hybrid Polymer Nanocomposites

Herein we report the tailoring of the band gap of polyvinyl alcohol (PVA)/graphene oxide (GO), PVA-Ag (silver), PVA/GO-Ag, and PVA/GO/Ag/GA (glutaraldehyde) employing ultraviolet (UV) irradiation. Nanocomposites were fabricated by the in situ solution casting method. Among fabricated, PVA/GO/Ag/GA was identified as the nanocomposite having enhanced properties. The structural and chemical studies confirm enhanced interfacial interaction and crosslinking between PVA and GO in the presence of GA. GA crosslinked PVA/GO-Ag nanocomposite shows a reduction in band gap and enhanced dc conductivity compared to other composites. Post-UV irradiation studies show PVA/GO/Ag/GA exhibits mechanical stability and good conductivity. The band gap of PVA/GO/Ag/GA decreased from 5.27 eV (unirradiated) to 2.66 eV for 24 h of UV exposure. As the exposure time increased to 48 h, the band gap increased to 5.16 eV and finally band gap decreased to 4.47 eV for 72 h of UV exposure. This reveals that though there is no linear variation in the energy gap with UV exposure time but accurate reproducibility was observed. This brings about the possibility of tailoring the band gap of PVA/GO/Ag/GA with better electrical conductivity (3.4 × 10⁻⁹ Sm⁻¹) and good mechanical stability which is very crucial for optoelectronic applications. Additionally, for 72 h of UV radiation exposure, the PVA/GO/Ag/GA composite demonstrates UV transmittance of 3.3%, underscoring its UV shielding capability.