Synthesis and Characterization of Micrometer-Sized, Polyaniline-Coated Polystyrene Latexes

Abstract

Poly(N-vinylpyrrolidone)-stabilized polystyrene (PS) latexes have been coated with thin overlayers of polyaniline (PANi) to produce electrically conductive “core−shell” particles. In this work we focused on the morphology of the PANi overlayer, the colloid stability of the coated latexes, and electrical conductivity. PANi-coated particles exhibit a nonuniform morphology as observed by scanning electron microscopy (SEM), in comparison with the relatively smooth polypyrrole overlayers synthesized in a previous study (Lascelles, S. F. et al., J. Mater. Chem. 1997, 7, 1339 and 1349). Disk centrifuge photosedimentometry confirmed that the PANi-coated PS latexes were weakly flocculated. The underlying PS latex “core” was quantitatively removed by solvent extraction, and SEM observations of the PANi residues revealed a “broken egg shell” morphology. Vibrational bands due to the PANi component were more intense in both the FT-IR and Raman spectra of the PANi-coated PS latexes, which is also consistent with the “core−shell” morphology. No reduction in the surface roughness of the PANi overlayer was observed when the rate of the aniline polymerization was decreased or if the latex surface was pretreated with either a thin polypyrrole overlayer or a layer of adsorbed surfactant. Similarly, only rough PANi overlayers were observed when coating a sulfonated PS latex. However, a more uniform deposition of PANi and a corresponding improvement of colloid stability were obtained using aniline hydrochloride monomer in the absence of added acid.

All-Acrylic Film-Forming Colloidal Polymer/Silica Nanocomposite Particles Prepared by Aqueous Emulsion Polymerization

“…For example, incipient flocculation induced by either the physical adsorption of silica nanoparticles 9 or the deposition of an ultrathin overlayer of a conducting polymer is readily detected. [61][62][63] For example, Colard et al monitored the depletion of an ultrafine silica sol from the reaction solution during the in situ formation of polymer/silica colloidal nanocomposite particles. 53 However, one drawback associated with DCP is that a single value for particle density must be determined and input into the software to obtain meaningful size distributions.…”

Conducting Polymer-Coated Latex Particles

“…[9] Moreover, the minimum conducting polymer loading required for well-defined ªegg-shellsº was around 5±6 % by mass, which corresponds approximately to the knee of the conductivity percolation threshold curve determined for compressed pellets of these composite latexes. [7,9] Hence these composite particles have high conductivities because electric current can easily pass through the overlayer of conducting polymer without ªsee-ingº the underlying low conductivity PS latex core. Most of our work [6±10] has focused on the use of micrometer-sized latexes, since scanning electron microscopy (SEM) studies of the surface morphology of the conducting polymer overlayer are much more straightforward.…”

Conducting poly(methyl methacrylate)/polyaniline (core/shell) particles for electrorheological fluids

“…The PANI shell was covered over the PMMA core by the method of Barthet et al [19]. Aniline was added to the suspension containing PMMA particles with sodium dodecylsulfate (SDS), and a small amount of hydroquinone was also added to the system in order to minimize the polymerization of aniline in the water phase.…”