Novel uses for conducting polymers: conducting polymer-paper composites

Abstract

Since their discovery in 1977, conducting polymers have attracted significant interest within the scientific community due to their various interesting properties and promising potential applications. The lack of mechanical processability of conducting polymers is however, a serious disadvantage. Paper is a widely used material with well-known chemistry. Unique and exciting opportunities exist to develop new polymer-paper composite materials which retain the properties of both the component materials. During the course of this project such materials were prepared and studied. A polypyrrole colloid was also prepared by a modification of a literature method. This colloid was spin cast and dried to enable its study by SEM. The colloid is made up of spherical particles 20-30 nm in diameter. A variety of polypyrrole-paper composites were prepared and studied. The best results in terms of conductivity were achieved when pyrrole was added to the paper sheet followed by the oxidant solution. The resultant polypyrrole layer completely encases individual fibres and follows the grain of the paper. Samples oxidised by iron(III) chloride are more conductive than the samples oxidised by ammonium persulfate. It is believed that this is because using iron(III) chloride as the oxidant results in a polymer that is fully doped and hence more conductive. The maximum conductivity achieved for a polypyrrole-paper composite was 2.52 S.cm-1. Poiyaniline-filter paper composites were also prepared using ammonium persulfate and iron(III) chloride solutions as oxidants. The best results in terms of fibre coating were achieved when aniline was added to the paper followed by the oxidant solution. The maximum conductivity for polyaniline-paper composites (3.09x10-4 S.cm-1) was achieved by using iron(lll) chloride as the oxidant solution. The samples were studied by a variety of methods including elemental analysis, scanning electron microscopy, cyclic voltammetry, infra-red spectroscopy and UV-vis spectroscopy. It is believed that the polypyrrole and polyaniline in the composite materials are bound to the paper fibres, but retain their chemical properties.