Control of static and dynamic hydrophobicity of solid surface and its application

Abstract

Technologies of hydrophobic coating on solid surface are important for various industrial items to impart functions such as antibeading, anti-rusting, anti-snow adhesion, self-cleaning, and lubrication. In recent, the demands of these functions are upgrading, and further improvements of performance are necessary. To meet today's requirements, detailed understandings on the relation between solid characteristics (such as structure, chemical composition, and their arrangement) and static/dynamic hydrophobicity is indispensable. So far, the research on this relation has been conducted in the part of fluid mechanics, tribology, and surface chemistry. However, recent researches revealed that static and dynamic liquid droplet behaviors are affected by nano-scale surface characteristics on hydrophobic solids, and the importance of the viewpoint from materials science is gradually increasing in this topic. This paper presents a review of recent studies on the relation between solid characteristics and static/ dynamic hydrophobicity, mainly of the past decade of our group.

Dynamic Measurement of the Force Required to Move a Liquid Drop on a Solid Surface

“…Most other methods applied in this field provide only information about static lateral adhesion forces or the roll-off angle. 11,41 In particular with the DAFI, F LA (v) could be measured spatially resolved. Thus, structured surfaces and gradients in surface tension can be quantified.…”

“…The lateral adhesion force was found to be linearly dependent on the velocity. Most other methods applied in this field provide only information about static lateral adhesion forces or the roll-off angle. , In particular with the DAFI, F LA ( v ) could be measured spatially resolved. Thus, structured surfaces and gradients in surface tension can be quantified. ,− Furthermore, variations of the force caused by pinning of the TPCL to single defects were resolved.…”

“…1−10 Investigating lateral adhesion forces, F LA , on drops is of interest for fundamental wetting science and industrial applications such as self-cleaning surfaces or paint spraying. 1,3,8,11 In the case of self-cleaning surfaces, drops should slide off easily. Thus, weak lateral adhesion is desired.…”

“…Sessile liquid drops on solid surfaces experience lateral adhesion owing to surface tension and contact angle hysteresis. The force needed to overcome lateral adhesion is commonly referred to as hysteresis force, (lateral) capillary force, (lateral) adhesion force, or simply retention or retarding force. − Investigating lateral adhesion forces, F LA , on drops is of interest for fundamental wetting science and industrial applications such as self-cleaning surfaces or paint spraying. ,,, In the case of self-cleaning surfaces, drops should slide off easily. Thus, weak lateral adhesion is desired.…”

Enhancing the Superhydrophobic State Stability of Chitosan‐Based Coatings for Textiles

“…Fluorocarbons in the form of adsorption films have the lowest solid/air surface energy values of any organic liquids 22. Moreover, surfaces with fluorocarbon coatings demonstrate outstanding tribological properties 23, 24. However, corresponding adsorption films of fluorocarbons could impart superhydrophobic properties to the surfaces only if they were deposited on a rough substrate5, 18, 25 with multimodal roughness.…”