Surface Characterization of Polyaniline-Coated Polystyrene Latexes

Abstract

The surface compositions of seven polyaniline (PAni)-coated polystyrene (PS) latexes have been investigated by X-ray photoelectron spectroscopy. This technique was used to assess the uniformity of the PAni overlayers deposited onto micrometer-sized, poly(N-vinylpyrrolidone) (PNVP)-stabilized PS latex particles under various synthesis conditions. Peak fitting of the N(1s) core-line spectra provided evidence for the presence of both PAni and the PNVP stabilizer at the surface of the PS latex. Nonuniform PAni coatings were obtained using conventional aniline polymerization conditions (aniline monomer, ammonium persulfate, 1.2 M HCl at 25 °C). In contrast, more homogeneous PAni coatings were obtained when polymerizing aniline hydrochloride at 0 °C in water. The relative proportion of PAni at the surface of the PS latex was estimated by comparing the surface nitrogen contents of the coated and uncoated PS latexes to that of a PAni “bulk powder” prepared in the absence of any latex. It was shown that the relatively rapid polymerization at room temperature resulted in nonuniform PAni coatings and reduced PAni surface composition. The maximum PAni coverage was found to be around 57−59%, which is much lower than the surface composition of 94−100% found for polypyrrole (PPy) deposited onto a similar micrometer-sized PS latex (Perruchot et al. Langmuir 1996, 12, 3245). These results indicate that the PAni coatings are much less uniform than the PPy overlayers. Finally, the improved uniformity of the PAni overlayers prepared using aniline hydrochoride in the absence of HCl is consistent with the higher coalescence temperature found for these PAni-coated PS particles in hot-stage optical microscopy studies.

Conducting Polymer-Coated Latex Particles

“…[20] These results were supported by SEM studies, which showed that PPY overlayers appeared far smoother than PANI overlayers.…”

Electromagnetic radiation shielding by composites of conducting polymers and wood

“…For composites containing conducting particles with a high aspect ratio, the percolation limit drops below 5 vol % of the conducting component. 21,22 The nonconducting particles coated with conducting polymers also have a lower percolation limit [23][24][25] compared with composites in which compact conducting particles are dispersed in the non-conducting matrix, where the formation of conducting pathways is much more difficult. In the case of coated sawdust, both of these effects are combined, and the observation of a percolation threshold below 5 wt % of conducting polymer is thus not surprising.…”

Electrochromic Properties of Polyaniline-Based Hybrid Organic/Inorganic Materials

“…16 In order to increase the processability and mechanical properties of PAni, significant efforts have been done in preparation of blends based on PAni with other appropriate polymers that have good physical properties, 17,18 such as polystyrene, 19 polyamide, 20 and polysaccharides like cellulose, starch and chitosan. [21][22][23] Recently, in addition of the mixture of PAni with other polymers, it has been sought to improve such properties through the preparation of hybrid organic/inorganic composites by the incorporation of metal oxides (such as WO 3 28 or mesoporous materials such as SBA-15 and MCM-41, 29,30 since they combine the advantages of conjugated conducting polymers and these fillers offering special properties arising from the combination of each component.…”