A conductive aqueous polymer suspension of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), or PEDOT:PSS, was used as the basis for an inkjet-printable and translucent conductive material. Several types of surfactants were used to achieve suitable particle sizes for inkjet printing, with Zonyl™ FS-300 non-ionic surfactant providing suitable surface tension, stability and dispersion. Viscosity was controlled using water and glycerol. Glycerol was also included as a humectant. 10 w/w% polar solvent (dimethyl sulfoxide) was used to increase conductivity, as a co-solvent and as a viscosity modifier. Carbon nanotubes, both single-and multi-walled, were dispersed in the ink to further improve its conductivity. The optimized ink was printed onto coated photo-paper and cellulose acetate (CA) substrates and characterized for ink layer thickness and conductivity. The effect of paper folding and peeling of an adhesive strip from the ink surface on the conductivity of the printed samples was also characterized. Optical microscopy showed that the conductive ink was contained almost entirely in the pores of the photo-paper coating layer and fibres, but remained as a film on the CA surface. In the case of photo-paper, failure occurred primarily at the coating-paper interface. The cohesive failure compromised the conductivity of the PEDOT:PSS layer contained in the coating. In the case of CA (within the coating layer), the PEDOT:PSS film's conductivity was not significantly affected by folding or peeling. This suggests that PEDOT:PSS is a robust conductive material well-suited to applications requiring significant flexibility.

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Poly(3,4-ethylenedioxythiopene): poly (styrene-sulfonate), or PEDOT:PSS, as well as singlewalled carbon nanotubes, were incorporated into an inkjet ink. Handsheets were prepared which contained varying amounts of TiO2filler, internal sizing agent, fixation agent, and either softwood or hardwood kraft pulp. The ink was jetted onto the handsheets to form conductive layers with apparent conductivity as high as 0.018 S/cm on internally alkyketene dimer-sized softwood kraft handsheets with no other additives. Internal sizing increased conductivity at low filler loadings by preventing PEDOT:PSS from penetrating into the substrate, resulting in a conductive ink film on the surface of the sample. Unsized handsheets allowed more rapid absorption, and therefore deeper penetration, of the PEDOT:PSS ink, which resulted in a more diffuse conductive layer. The inclusion of a polyethyleneimine retention aid for TiO2filler decreased conductivity significantly even in unfilled sheets by interaction with PSS-counterions. A positively charged fixation agent, poly(diallyldimethylammonium) chloride, reduced PEDOT conductivity through the retention of nonconductive PSS-anions.

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Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), or PEDOT:PSS, and singlewalled carbon nanotubes (SWCNTs) were incorporated into an inkjet ink. The combination of PEDOT, a conjugated, conductive polymer, and highly conductive CNTs, yielded a conductive film after printing and curing of the ink. Several paper types were used as substrates for depositing printed patterns of the PEDOT:PSS/SWCNT ink. Wide variability in conductivity was observed for different commercial paper types, ranging from a maximum 0.9 S/cm on Epson ® Premium Photo cast-coated glossy paper to 3 × 10 -5 S/cm on Epson ® Premium Presentation coated cardstock. Increasing the SWCNT content of the ink improved conductivity on a non-permeable cellulose acetate substrate to a point, after which the combined effects of ink filtration and jetting limited the number of nanotubes delivered to the substrate. On permeable paper, the irregularity of the substrate overcame the beneficial effects of SWCNTs as "bridges" between conductive PEDOT regions. Correlations between the substrates' physical structure and conductivity were established for the printed sheets, with densely coated sheets presenting the highest conductivity, and porous sheets the lowest.