Electrically conductive textile coating with a PEDOT-PSS dispersion and a polyurethane binder

Electrically conductive textile coatings have been prepared by the addition of a dispersion of poly(3,4-ethylenedioxy thiophene)-polystyrene sulfonate (PEDOT-PSS) and ethylene glycol to a polyurethane-based coating formulation. The formulations were designed to have similar viscosities, measured with a rheometer using a cone-and-plate set-up. The formulations were applied to woven poly(ethylene) terephthalate substrates using a direct coating method. The concentration PEDOT-PSS in the finished coatings varied between 0.7 and 6.2 wt%, the coating deposit between 19 and 155 g/m(2) and the drying procedure between 4 hours at 20 degrees C and 10 minutes at 150 degrees C. Surface resistivity was measured with a ring probe and surface topology was addressed with scanning electron microscopy (SEM). The PEDOT-PSS concentration had a large effect on the resistivity, which dropped by five orders of magnitude with an increased concentration. The steepest decrease occurred between 1 and 3 wt% PEDOT-PSS, indicating a percolation threshold. An increased coating deposit resulted in a resistivity drop by a factor 10, but no significant effect on the resistivity of the samples could be ascertained by variation of the drying conditions when samples had been subjected to subsequent annealing.