Effect of roughness geometry on wetting and dewetting of rough PDMS surfaces.

摘要: Rough PDMS surfaces comprising 3 μm hemispherical bumps and cavities with pitches ranging from 4.5 to 96 have been fabricated by photolithographic molding techniques. Their wetting dewetting behavior water was studied as model for print used in additive manufacturing printed electronics. A smooth surface control. For a given pitch, both bumpy cavity exhibit similar static contact angles, which increase the roughness ratio increases. Notably, observed angles are shown be consistently larger than calculated Wenzel attributable pinning of droplets into metastable states. Optical microscopy reveals that lines on distorted microtextures, at lead edges cavities. Vibration sessile smooth, bumpy, results same angle, 110°-124° ∼91°. The suggest all three stable states after vibration pin area rough surfaces. This conclusion is supported visual inspection before vibration. importance location rather energy angle discussed. droplet examining receding motion line evaporating very dilute rhodamine dye solution these reveal dragged it recedes, whereas dragging not visible drag created toward process also velocity-dependent advancing experiments.