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The effect of polyvinylpyrrolidone on the optical properties of the Ni-doped ZnS nanocrystalline thin films synthesized by chemical method

We report the optical properties of polyvinyl-pyrrolidone (PVP) and the influence of PVP concentration on the photoluminescence spectra of the PVP (PL) coated ZnS :Ni nanocrystalline thin films synthesized by the wet chemical method and spin-coating. PL spectra of samples were clearly showed that the 520nm luminescence peak position of samples remains unchanged, but their peak intensity changes with PVP concentration. The PVP polymer is emissive with peak maximum at 394nm with the exciting wavelength of 325 nm. The photoluminescence exciting (PLE) spectrum of PVP recorded at 394nm emission shows peak maximum at 332 nm. This excitation band is attributed to the electronic transitions in PVP molecular orbitals. The absorption edges of the PVP-coated ZnS :Ni0.3% samples that were shifted towards shorter wavelength with increasing of PVP concentration can be explained by the absorption of PVP in range of 350nm to 400 nm. While the PVP coating does not affect the microstructure of ZnS :Ni nanomaterial, the analyzed results of the PL, PLE, and time-resolved PL spectra and luminescence decay curves of the PVP and PVP-coated ZnS :Ni samples allow to explain the energy transition process from surface PVP molecules to the Ni2+ centers that occurs via hot ZnS.

Synthesis, properties and application of polyindole/TiO2 nanocomposites

Nanocomposites of polyindole (PIn) and TiO2 were prepared by chemical polymerization. The morphology of nanocomposite particles was studied by scanning electron microscopy and transmission electron microscopy. The chemical structure of conducting polymers in nanocomposites was characterized by FTIR and Raman spectra. The thermal analysis showed that all conducting polymers in the nanocomposites were stable at more than 600°C. The corrosion protection of the nanocomposites was investigated.

Double corrosion protection mechanism of molybdate-doped polypyrrole/montmorillonite nanocomposites

Nanocomposites based on polypyrrole (PPy) doped with molybdate (PPy(MoO4)) and montmorillonite (MMT) were prepared by chemical polymerisation. The morphology of nanocomposite particles was studied by scanning electron microscopy. The chemical structure of conducting polymers (CPs) in nanocomposites was characterised by Raman spectroscopy. The thermal analysis showed that all CPs in the nanocomposites were stable for more than 500°C. Energy diffraction X-ray showed that the amount of Mo in element the PPy(MoO4)/MMT nanocomposite was 5.55%. The corrosion protection mechanism of the nanocomposites was investigated by electrochemical methods, showing that MMT acted as a barrier layer in nanocomposite and molybdate as an inhibitor for corrosion protection of metal.

Thin films containing Mn-doped ZnS nanocrystals synthesised by chemical method and study of some of their optical properties

In this article, we present the optical properties of thin films containing Mn-doped ZnS nanocrystals synthesised by the chemical method. The ZnS nanoparticles within the polymer matrix (polyvinyl alcohol) were investigated by SEM and TEM images and analysed by X-ray diffraction. The effect of polymer concentration on the direct band gap of Mn-doped ZnS thin films was calculated from the data for absorption measurements. The values of the band gap are in the range of 3.73–3.90 eV. In addition, we discuss the photoluminescence of these films.

Electronic properties of the polypyrrole-dopant anions ClO 4 − and MoO 4 2− : a density functional theory study

The conductive properties of polypyrrole chains doped with ClO4− or MoO42− anions and the existence of polarons and bipolarons in these doped polypyrrole chains were investigated by performing computational calculations based on density functional theory (DFT). Doping with these anions was found to decrease the band gap of the polypyrrole. Theoretical calculations revealed that changing the type of oxidative agent applied does not affect the conversion of polypyrrole into a conducting polymer, but the conductivity of the doped polypyrrole does depend on the ratio of oxidant to polypyrrole.

Synthesis and characterization of polythiophenes from hydrazone derivatives sidegroups

Polythiophenes with various substituted hydrazone side groups were synthesized using a chemical oxidative coupling reaction. Analyses of IR and NMR spectra confirmed the expected structure of new synthesized polymers and confirmed suitability of the suggested synthetic route. Surface properties, morphology and thermal stability of the prepared polymers were studied by SEM and TGA methods. Two derivatives were found to have a good solubility in several water-miscible solvents. They can be used as active materials in electrochromic and electronic devices.