A Study of Vapor Deposited PVDF/TiO₂ Nanoparticle Films by XPS

In this investigation, thermal vapor deposition was used to synthesize films of polyvinylidene fluoride (PVDF) containing nanoparticles of the ceramic titanium dioxide (TiO₂). This ferroelectric polymer has shown promise as a capacitor dielectric material with possible enhanced electrical properties when combined with ceramic nanoparticles. The films were synthesized starting from a mixture of PVDF and TiO₂ (rutile phase) dissolved in dimethylformamide (DMF) solvent. The PVDF-TiO₂ mixture was vapor deposited onto a Si wafer. The temperature during the deposition was approximately 400 °C and the deposition time was 15 min. The deposited films were characterized using x-ray photoelectron spectroscopy (XPS). It is noted that various starting mixtures and deposition parameters were investigated. The spectra reported here are from films from two different initial PVDF/TiO₂ mixtures (prior to deposition). For the maximum concentration of TiO₂ in the deposited films, the Ti atomic concentration is just under 10%. Analysis from XPS shows a defluorination of the films (C/F ratio >1) from the deposition process, with the final film being a mixture of PVDF and polyvinyl fluoride (PVF). It is also noted that energy dispersive spectroscopy (EDS) and atomic force microscopy (AFM) show that the TiO₂ nanoparticles are homogeneously distributed in the films. The reported XPS spectra include survey and high resolution scans of the major photoelectron peaks.