ANODIC CODEPOSITION OF POLYPYRROLE AND DISPERSED TIO2

A dispersion of TiO2-particles (anatase, 0.4-mu-m) in electrolytes containing 0.1 M pyrrole yields a composite material polypyrrole/TiO2 upon galvanostatic (0.5-2 mA cm-2) electrodeposition at platinum - or stainless steel-anodes under strong convection. The filler is distributed evenly in the PPy-matrix. The concentration of TiO2 in the new composite (c(C)) is up to 10 vol% (17 wt.%); it is therefore appreciably higher than in the cathodically plated composite with a metal matrix at the same concentrations of TiO2 in the electrolyte (c(E)). Doping/undoping of the polypyrrole matrix is not influenced by the presence of the TiO2 in the composite. The specific conductivity decreases stronger than it is expected from the volume fraction of the practically nonconducting component. Photoelectrochemical response is due to the TiO2, A codeposition mechanism is proposed, according to which the particles impinging the growing polypyrrole layer are mechanically captured even at low c(E). At higher c(E), further codeposition is achieved according to a mechanism which was originally proposed by Guglielmi for electroplated metal matrices. It suggests a two step adsorption process. This explains the dependency of c(C) on c(E) and the influence of the current density.