Fabrication of poly(p-phenylene vinylene) (PPV) nanoheterocomposite films via layer-by-layer adsorption

The fabrication of polyelectrolyte multilayer film architectures composed of a polycation precursor (Pre-PPV) of the electroluminescent poly(p-phenylene vinylene) (PPV) and two different counter-polyanions, cellulosesulfate and poly(vinylsulfate), are reported. All multilayers were characterized by UV/VIS-spectroscopy and X-ray reflectometry. Due to the differences in spatial arrangement of charged groups, rigidity, and conformation of the polyanions, the corresponding multilayer films differ in properties such as average thickness increments and surface roughness. The adsorbed amounts per layer can be adjusted by addition of inorganic salts. Thermal conversion of Pre-PPV to PPV is achieved already slightly above 100 °C, yielding identical absorption spectra for after either 3 h at 160 °C or 20 h at 120 °C. The heat treatment causes the film thickness to be reduced by 24–40% due to elimination of dimethylsulfide and HCl and also the loss of water, but the films stay optically transparent.