Semi-interpenetrating polymer networks based on modified cellulose and poly (3,4-ethylenedioxythiophene)

The synthesis of semi-interpenetrating polymer networks (sIPN) prepared from an insulating derivative of a natural polymer, cellulose acetobutyrate (CAB), and a conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT) are described. The direct current conductivity of the obtained materials depends upon the ratio of the PEDOT to the CAB. A percolative behaviour following power-law dependence was observed. From direct current conductivity, a mass percolation threshold of 3.6% (w/w) was obtained. Also, two critical exponents are determined according to the percolation in three dimension theory. The dynamics of the charge propagation are studied by chronoamperometry, The time dependence of the current did not follow Fick's law. The chronoamperograms were analysed within the framework of electrochemically stimulated conformational relaxation (ESCR) model in which the oxidation reaction could be controlled by the relaxation of the polymer or by the diffusion of counter-ions inside the polymer. For the sIPN based on CAB and PEDOT, a diffusion controlled oxidation was observed. A potential threshold E-* of 0.06 V versus Ag/AgCl and a kinetic constant of charge propagation b of 2.6 +/- 0.2 x 10(-2) s(-1) were obtained. (C) 2002 Elsevier Science B.V. All rights reserved.