The validity of triple contact line theory from hydrophilic to superhydrophobic surfaces

Abstract

The anisotropic droplet formulation is generalized from hydrophilic to superhydrophobic surfaces. An experimental method to calibrate the ellipsoidal droplet volume on both hydrophilic and hydrophobic surfaces is presented. A broad range of contact angles (CAs) is produced on the copper and stainless-steel surfaces using femtosecond laser patterning. The effects of line spacing between the laser scanning on the formation of anisotropic CAs are discussed. The comparative study of the evolution of anisotropic CAs and droplet’s spreading dynamics are studied on both surfaces. According to the triple contact line (TCL) theory, CAs are determined by the TCL between droplet and surface rather than the contact area. We presented the mathematical formalism and the experimental validity of the TCL theory on ellipsoidal droplets over a broad range of CAs, from as low as 37°–172°. This work experimentally validated the TCL theory over a broad range of CAs with good confidence.

Shaping in the Third Direction: Self-Assembly of Convex Colloidal Photonic Crystals on an Optical Fiber Tip by Hanging Drop Method

“…These important forces involved in the mechanical equilibrium of the colloidal droplet hanging from the tip of the optical fiber, namely gravity and capillary force interplay at the boundary between the liquid, the air, and the optical fiber (triple contact line, TCL) [ 24 ] ( Figure 1 g). Deviation from the ideal shape of the triple contact line (a circle) caused by surface defects in the optical fiber (roughness and chemical impurities adsorbed on the surface) leads to deviation from the axi-symmetry of the self-assembled colloidal crystal.…”

“…These important forces involved in the mechanical equilibrium of the colloidal droplet hanging from the tip of the optical fiber, namely gravity and capillary force interplay at the boundary between the liquid, the air, and the optical fiber (triple contact line, TCL) [24] (Figure 1g). Deviation from the ideal shape of the triple contact line (a cir- These important forces involved in the mechanical equilibrium of the colloidal droplet hanging from the tip of the optical fiber, namely gravity and capillary force interplay at the boundary between the liquid, the air, and the optical fiber (triple contact line, TCL) [24] (Figure 1g). Deviation from the ideal shape of the triple contact line (a circle) caused by surface defects in the optical fiber (roughness and chemical impurities adsorbed on the surface) leads to deviation from the axi-symmetry of the self-assembled colloidal crystal.…”

Microstructured Ultra-black Thin Stainless-Steel Sheets Fabricated by Sagnac Interferometric-Based Ultrafast Laser Patterning

“…Alternatively, an emerging method, fabrication via pulsed lasers, proved to be an attractive tool for fabricating nanostructures on different surfaces, − with a wide range of applications in controlling wettability, − surface coloring, − subwavelength structures, − surface-enhanced Raman spectroscopy, tuning reflectivity properties, etc. As these structures are surface modifications made of the same material within a depth of a few microns, they possess the intrinsic stability to sustain harsh environments .…”