Percolation on a self-assembled network: Decoration of polyethylene gels with conducting polymer.

Abstract

Conducting gels of ultrahigh molecular weight polyethylene and the soluble conjugated polymer poly(3-octylthiophene), P3OT, were prepared by thermoreversible gelation from semidilute solutions in decalin, and subsequent doping with iodine. We report the results of frequency-dependent complex conductivity measurements (from 1 kHz to 1 GHz) on these gels. Although the volume fraction of P3OT in the gel range from less than 5\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}4}$ to about 3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}2}$, we found evidence of connected conducting paths with no indication of a percolation threshold. The results are discussed in terms of adsorption of the P3OT onto the preformed polyethylene gel network which organizes the P3OT into connected paths at concentrations well below the nominal percolation threshold.