Temperature, polypyrrole film stability

The poor stability on exposure to air and water, particularly at elevated temperatures, which results in a reduction in conductivity, also poses problems. In the case of polypyrrole it has been found that conductivity can, however, be maintained either by the drastic measure of storing under the protective layer of the inert gas argon or embedding polypyrrole film in a matrix of an epoxide resin-glass-fibre composite. 

Figure 16.17. Thermal stability of polypyrrole film prepared at —20°C and subjected to heat treatment at various temperatures, (a) conductivity and --0-- Cl content measured by EPMA and (b) distribution of Cl measured by EPMA across the film section. Adapted from Synth. Mel. 14, 61 (1986),with permission of Elsevier Science S.A., Lausanne.

Truong V-T (1992) Thermal degradation of polypyrrole effect of temperature and film thickness. Synth Met 52 33-44 Van Beusichem B, Ruberto MA (2005) Introduction to polymer additives and stabilization. A presentation to product quality research institute http //www.pqri.org/... /posters/Polymer Additives PQRI Poster.pdf Accessed 26 June 2011 Van Krevelen DW, Nijenhuis KT (2009) Properties of polymers. Their correlation with chemical structure their numerical estimation and prediction from additive group contributions, 4th edn. Elsevier, Amsterdam Wang Y, Rubner MF (1990) Stability studies of the electrical conductivity of various poly (3-alkylthiophenes). Synth Met 39 153-175... 

The electrochemical polymerization method was used to prepare layers of conductive polymers on electrodes pre-coated with another conductive polymer or using films of a conductive polymer as electrode. This was the method used to prepare a composite of poly acetylene and polypyrrole [150,151] A sandwichlike composite with layers of polypyrrole adhered to polyacetylene was obtained using undoped polyacetylene electrodes. The use of doped polyacetylene induced pyrrole polymerization in the bulk of the film. A strong improvement in the stability of polyacetylene was observed exposure to ambient temperature of 30 days or to water for 20 minutes did not reduce the conductivity of both materials. 

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