Preparation and hydrophobicity of solid–liquid bulk composite using porous glass and fluorinated oil

• Published in: Journal of materials science Vol. 50; no. 23; pp. 7760 - 7769
• Main Authors: Takada, Yasuhiro, Sakai, Munetoshi, Isobe, Toshihiro, Matsushita, Sachiko, Nakajima, Akira
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-12-2015; Springer; Springer Nature B.V
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; coatings; Composite materials; Contact angle; Crystallography and Scattering Methods; Droplets; energy; Energy dissipation; Fluid dynamics; Fluorination; Glass; Glass plates; Helium; Hydrophobicity; Impregnation; Materials Science; oils; Original Paper; Particle image velocimetry; Polymer Sciences; Pore size; Porosity; silica; Silicon dioxide; Solid Mechanics; Surface energy; Turbulent flow; Velocity measurement; Viscosity; Water drops; Water flow; Wetting; Water Droplet; Internal Fluidity; Contact Angle; Particle Image Velocimetry; Porous Glass
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-015-9346-9

Hydrophobic porous glass plates were prepared by coating a fluorosilane (FAS17) onto a commercial porous glass (average pore size, approx. 1 μm) with surface modification by colloidal silica (approx. 100 nm). Then porous glass–fluorinated oil composites were prepared by subsequent impregnation of two fluorinated oils with similar surface energy but differing viscosity. Both the sliding angle (~5° → ~0°) and contact angle (~150° → ~115°) were decreased by impregnating fluorinated oil into the porous glass. The composites possessed excellent sustainability of their small sliding angle under exposure in turbulent water flow. The composite exhibited higher sliding velocity than that of a normal hydrophobic coating. The composite with high-viscosity oil exhibited a lower sliding velocity for a water droplet than that with low-viscosity oil. Particle image velocimetry revealed that the dominant sliding mode for water droplets on the composites was slipping. Results suggest that viscous dissipation at the wetting ridge (oil meniscus at the three-phase contact line) plays an important role in the moving behavior of water droplet on the composites. The superiority in dynamic hydrophobicity for the composites was retained even when the droplet was sandwiched between two parallel samples.