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.