Characterisation of PEDOT-PSS Inks and Products

Materials used for the case study included PEDOT PSS poly(3,4-ethylenedioxythiop hene) poly(styrenesulfonate) 1.3 %wt in water (Sigma Aldrich), Dimethyl Sulfoxide (Fischer Scientific) and Surfynol (AirProducts). For drop cast conductivity and surface tension analysis, PEDOT PSS/DMSO(0-5 wt%) and PEDOT PSS/DMSO(0-5 wt%)/Surfynol mixtures were prepared at ambient conditions and allowed to mix in a sonication bath for 24 hours Samples were drop spread onto cleaned glass slides between the ends of conducting aluminium tapes. All samples were allowed to anneal in ambient conditions for 30 minutes at 130 °C. 

Surface tension was determined via the pendant drop method using a Kruss EasyDrop. The liquid was suspended from an 1832 pm needle with equatorial and neck diameters measured for the largest stable drop. The surface tension was calculated using the relationship  

3 Characterisation of Carbon Nanotube - PEDOT PSS Nanocomposite Products 

An amount of 0.023 g Elicarb multiwall carbon nanotubes (MWNT), supplied by Thomas Swan Ltd., was added to 25.47 g of 1.3 wt% PEDOTrPSS solution in water. The mixture was sonicated for 1 hour and it was then subjected to high shear mixing at 18,000 rpm for 1 hour. The resulting ink had a viscosity of 50 mPa-s. Before further processing, it was further diluted with de-ionised water by 5 1, yielding a reduced viscosity of 8.8 mPa-s. The diluted PEDOTrPSS ink had a surface tension of 68.3 mN/m either with or without the prescribed concentration of MWNT. 

The fabrication method involved drop spreading on a Melinex film substrate. The drops were produced using a syringe pump at a constant flow rate of 86.5 ml/h, and a pulse time of 0.6 s. The syringe had a 36 gauge steel needle with a 60 pm inner diameter, and 180 pm outer diameter. The experimental procedure was repeated for paper and cardboard substrates. In all cases, printing was carried out incorporating 1 print pass (1 printed drop), 2 print passes (2 printed drops overlaid), 3 print passes (3 printed drops overlaid) and 4 print passes (4 printed drops overlaid). 

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