X-ray Photoelectron Spectroscopy Characterization of Submicrometer-Sized Polypyrrole−Polystyrene Composites

Abstract

The surface compositions of a series of five polystyrene−polypyrrole (PS−PPy) composites and three reference materials (the original poly(ethylene glycol) (PEG) stabilizer, the uncoated PEG-stabilized PS latex, and PPy chloride bulk powder) were examined by X-ray photoelectron spectroscopy (XPS). The uncoated PEG-stabilized PS latex particles had a narrow size distribution with a mean diameter of 129 nm. The N1s XPS signal is a unique elemental marker for the PPy component and was therefore used to determine its surface concentration. As the PPy loading on the PS latex particles was increased from 4.2 to 28.1 wt % the relative intensity of the N1s signal increased, as expected. However, surface doping levels calculated from the Cl/N atomic ratios were relatively low, suggesting that some oxidative degradation of the deposited PPy component had occurred. Raman studies also indicated decreased doping levels at low PPy loadings. Close inspection of the C1s envelopes indicated that the composite particles did not have the expected core−shell morphology, since even at the highest PPy loading these XPS spectra were very similar to that of the original PS latex. These observations were confirmed by scanning electron microscopy (SEM) studies, which revealed the presence of discrete PPy nanoparticles of 20−30 nm diameter. Finally, it was found that more uniform PPy overlayers could be prepared by modifying the synthesis conditions. Thus, reducing both the total latex surface area and the pyrrole monomer concentration led to PS−PPy particles with a much improved core−shell morphology, as judged by both XPS and SEM.

Novel Pickering Emulsifiers Based on pH-Responsive Poly(2-(diethylamino)ethyl methacrylate) Latexes

“…Figure 3 shows the 1 H NMR spectra recorded in CDCl 3 for a purified PEGMAstabilized linear PTBAEMA latex (entry 9 in Table 1; spectrum A) and a charge-stabilized linear PTBAEMA latex (entry 11 in Table 1; spectrum B). The additional signal observed at 3.7 ppm in the former case is assigned to the oxyethylene protons due to the PEGMA chains; 38,43 comparison of this peak integral with that signal at due to the oxymethylene protons adjacent to the ester group of the PTBAEMA residues indicated a PEGMA content of approximately 1.8 mol %. Given the comparable particle diameters obtained for the cross-linked and linear PTBAEMA particles (see Table 1), the former latexes should contain similar amounts of PEGMA stabilizer to the latter.…”

Polypyrrole-Coated Granules for Humic Acid Removal

“…By counting the electrons for various BEs, a corresponding spectrum is obtained. Since each value of the BE is characteristic for a given element, and each peak area is proportional to the number of atoms being present in the solid matter studied (23,28), the chemical elemental composition of the sample surface is therefore determined by calculating the respective contribution of each peak area. Appropriate data processing then leads to the determination of the chemical-bound nature that exists between these elements.…”

Synthesis and characterization of polypyrrole doped with anionic spherical polyelectrolyte brushes

“…The investigations on the structure and properties of PPy have been performed by many techniques. X-ray photoelectron spectroscopy (XPS) proved to be particularly useful in the surface characterization of PPy [12][13][14] because it has a typical sampling depth of 2-10 nm. Fourier transform infrared spectroscopy (FTIR) is a convenient technique to monitor changes in the structure of conducting polymer chains [15,16].…”