Substrate viscosity-dependent droplet behavior on slippery surface

The interaction of droplets with surfaces that exhibit slippery behavior is not only an interesting natural phenomenon but also finds applications in diverse areas. Contrary to the commonly used liquid-infused surface for slippery surface fabrication, in this paper, a slippery surface is made by mixing the two components of polydimethylsiloxane and silicone oil in a ratio of 1:4. The study reveals the viscosity of the silicone oil in the mixture is found to have a profound effect on the suppression of the coffee-ring effect and sliding angle dependent velocity behavior. The droplet impact studies on the fabricated slippery surface illustrate that the viscosity of the silicone oil in the matrix plays an important role in the droplet dynamics on the surface, whether it is oscillation or partial rebound. In addition, the dimension of the droplet splitting during the partial rebound regime can be controlled by varying the Weber number. The present approach of creating slippery surfaces and controlling the droplet dynamics on its surface by varying the viscosity can find a plethora of applications, ranging from open microfluidics to medical devices. • Four substrates composed of a PDMS-silicone oil mixture are fabricated. • Surface wettability of the substrates is characterized. • The influence of surface wettability on the droplet impact is studied. • Spreading factor and correlation of Weber number to viscosity plotted.