Oscillations of aqueous PEDOT:PSS fluid droplets and the properties of complex fluids in drop-on-demand inkjet printing

作者：Hoath Stephen D^*; Hsiao Wen Kai; Martin Graham D; Jung Sungjune; Butler Simon A; Morrison Neil F; Harlen Oliver G; Yang Lisong S; Bain Colin D; Hutchings Ian M

来源：Journal of Non-Newtonian Fluid Mechanics, 2015, 223: 28-36.

DOI：10.1016/j.jnnfm.2015.05.006

• Inkjet printing
• PEDOT:PSS
• Shear thinning fluids
• Drop oscillations
• Dynamic surface tension
• Shear thinning recovery time

Shear-thinning aqueous poly(3,4-ethylenedioxythiophene): poly(styrene sulphonate) (PEDOT:PSS) fluids were studied under the conditions of drop-on-demand inkjet printing. Ligament retraction caused oscillation of the resulting drops, from which values of surface tension and viscosity were derived. Effective viscosities of <4 mPa s at drop oscillation frequencies of 13-33 kHz were consistent with conventional high-frequency rheometry, with only a small possible contribution from viscoelasticity with a relaxation time of about 6 mu s. Strong evidence was found that the viscosity, reduced by shear-thinning in the print-head nozzle, recovered as the drop formed. The low viscosity values measured for the drops in flight were associated with the strong oscillation induced by ligament retraction, while for a weakly perturbed drop the viscosity remained high. Surface tension values in the presence of surfactant were significantly higher than the equilibrium values, and consistent with the surface age of the drops.

• 出版日期2015-9