Study of structural, optical and dielectric properties of ZnO/PVDF-based flexible sheets

This study demonstrates the remarkable improvement in structural, optical and dielectric properties of flexible sheets of polymer-based zinc oxide nanocomposites (PB-ZnO-NCs) synthesized by co-precipitation method. The X-ray diffraction patterns show the development of ZnO (100), ZnO (002), ZnO (101) and ZnO (102) diffraction peaks. The variation in peak intensities and crystallite sizes are associated with increasing wt.% of ZnO nanofillers. The FTIR analysis confirms the presence of vibrational modes of PVDF, ZnO and O-H groups and shows strong bonding between PVDF and ZnO, when ZnO is more than 20wt.%. The SEM microstructural analysis of polymer is appeared just like microfibers which is changed into cloudy microstructure when 10 wt.% ZnO nanofillers are mixed, however, the surface morphology strongly depends on increasing wt.% of ZnO nanofillers. The small shift in absorption edges and increasing values of absorption for PVDF and ZnO depend on the increasing wt.% of ZnO nanofillers. The values of energy band gap are found in the range from 5.69-5.47 eV and 3.65-3.38 eV for PVDF and ZnO respectively. Dielectric measurements demonstrate a sharp increase in dielectric permittivity with relatively low loss factor. The static value of dielectric constant at 100 Hz is found to be 13.88 for sample having 50 wt.% ZnO nanofillers which is 4.2 times greater than PVDF and shows relatively low value of loss factor. The observed AC conductivity of synthesized PB-ZnO-NCs having 50 wt.% ZnO and 50 wt.% PVDF is found to be 2.16×10^-5 S/m which is 3.2 times larger than PVDF at 1×10⁶ Hz. Results indicate that a chain of polymer matrix arises due to defects and capsulated microstructures, increased with increasing wt.% of ZnO nanofillers which make the NCs more flexible, strengthen and conductive.