Forces at superhydrophobic and superamphiphobic surfaces

Publication date: Available online 10 December 2019Source: Current Opinion in Colloid & Interface ScienceAuthor(s): Mimmi Eriksson, Agne SwerinAbstractForces exerted at surfaces and interphases due to formation of gaseous (air or vapor) bridges describe the extreme liquid-repellence in superhydro- and amphiphobicity. The neighboring research areas oγAf liquid capillary bridges and that of interactions between hydrophobic surfaces are highly valuable reference systems. We review recent findings with particular focus on the three-phase contact line and surface forces. While macroscopic contact angles (>150°), low contact angle hysteresis (<10°, but can be high; parahydrophobic or petal type) and low roll-off angle (≤5-10°) are adequate criteria for superhydrophobicity (SH) and superamphiphobicity (SA) for most studies, a detailed understanding requires a view related to mechanisms. Experimental studies of liquid drop-substrate and particle-substrate adhesion in hydrophobic, SH and SA systems are summarized by relating measured forces to the wetting tension, γcosθ. A low wetting tension value is a necessary but not sufficient criterion for SH and SA systems.The picture emerging from detailed forPVce-distance studies is that extreme liquid-repellence in SH and SA systems is a progression of liquid-repellence due to hydrophobicFpinity, in which force curves can be explained by capillary forces of constant volume of the gaseous capillary. In SH and SA, neither the capil...
Source: Current Opinion in Colloid and Interface Science - Category: Chemistry Source Type: research