Potential Applications of Conducting Polymer Colloids

Abstract

We review the current literature in the field of conducting polymer colloids. Specifically, we focus on aqueous colloidal dispersions of two relatively air-stable conducting polymers, polypyrrole and polyaniline, and discuss some of our recent advances at Sussex. Such colloids are usually stabilised with respect to particle aggregation by an outer layer of adsorbed, solvated polymeric surfactant. The chemical nature of this surfactant largely determines the dimensions and morphology of the conducting polymer particles. Polypyrrole colloids generally have a spherical morphology and a relatively particle size distribution whereas polyaniline colloids tend to have non-spherical polydisperse ”rice-grain” morphologies. Very recently we have reported that small silica particles can also be utilised as effective dispersants for polyaniline or polypyrrole. In this system the silica particles are ”glued” together by the conducting polymer component to give sub-micronic conducting polymer-silica composites which exhibit an unusual ”raspberry” morphology. All the above dispersions have been characterised by a wide range of techniques, including electron microscopy, photon correlation spectroscopy, disc centrifugation, solid-state conductivity measurements, thermogravimetry, and both F.T.I.R. and visible absorption spectroscopy. Various potential applications of these conducting polymer colloids will be discussed, with particular emphasis given to their use in immunodiagnostie assays.