document: Equilibrium surface tension was measured at 21°C with a SITA pro line t-15 bubble tensiometer. Rheological measurements were performed with an ARES rheometer at shear rates up to 15s−1 and with a piezo axial vibrator [21] (PAV) at frequencies up to 6kHz. Table 1 shows the measured values of viscosity (the real component η′ of complex viscosity) at 1s−1 and 4000s−1 and of surface tension for the solutions with and without the surfactant mixture. For the most concentrated (1.1wt%) solution, viscosity fell from >60mPas at low shear rate to about 4mPas at the highest shear rates. The PEDOT:PSS fluids also exhibited elasticity that steadily reduced with increasing frequency [4]. All the aqueous PEDOT:PSS solutions shear-thinned significantly, but the presence of surfactants did not affect the trends in the rheological behaviour, particularly at the higher frequencies (10–4000s−1).
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