Effect of characteristic dimension of surface structure and particles on the contact line motion of sessile suspended droplet evaporation

The three-phase contact line (TPCL) motion during evaporation of nanofluid sessile droplet was experimentally investigated to reveal the effect of characteristic surface structure and dimensions of contained materials on evaporation profiles. Nano and microstructured surfaces were prepared through chemical treatment and two sizes of SiO2 spherical particles were used as deposition materials. The contact angle and contact base radius profiles were studied through captured side view images and the sessile droplet method. Discontinuous TPCL motion was observed on micro/nano hierarchical structure, while continuous contact line receding during evaporation was seen on nanostructured surface. In addition, nanofluid with low particle concentration showed large contact angle and contact radius jump relative to dense nanofluid. This finding shows that the increase the amount of deposited materials on the TPCL regions should lead the undeformable liquid-vapor interface, and it showed opposite trend compared to the result reported by flat surface. The result found in this study will help to understand the deposition patterns on the superhydrophobic surface which is an important issue for evaporation-driven supraparticles fabrication.