Influence of Processing Conditions and Material Properties on Electrohydrodynamic Direct Patterning of a Polymer Solution

Abstract

An electrohydrodynamic (EHD) patterning method was utilized to obtain high-resolution line patterns in a low electric field regime without an additional mechanical drawing process. Molecular weight and weight percent of a polymer were selected as key parameters to reduce the voltage. EHD patterning was performed using polyethylene oxide (PEO) solutions. The threshold voltages (V (th)) to initiate jet ejection are almost the same for all solutions. A method verified in this study, reducing the driving voltage (V (d)) just after the initiation of the jet at the threshold voltage, can make a very thin, continuous jet, while increasing molecular weight and weight percent were enabled to further reduce the input voltage. As the voltage reduction ratio (V (d)/V (th)) is decreased, the jet behaves like a solid rather than a liquid due to its fast solidification. The line width of the resultant line pattern could be tuned from 50 nm to 10 mu m depending on the substrate moving speed. Contour maps were also developed that show the pattern mode variation as a function of the voltage reduction ratio and key parameters. The results show that well-defined PEO line and grid patterns can be fabricated via the proposed EHD direct patterning under appropriate conditions.