The Lotus Effect:  Superhydrophobicity and Metastability

Marmur, Abraham

doi:10.1021/la036369u

Cited by 1,034 publications

(702 citation statements)

References 24 publications

Supporting

Mentioning

680

Contrasting

Unclassified

Order By: Relevance

“…Consequently, easy removal of a drop from a surface requires minimization of hysteresis. In addition, it is reasonable to assume 44,116,117 that the drop will quickly react to the removing force if its actual contact area with the solid (the 'wetted area') is as small as possible.…”

Section: Surface Innovations Volume 2 Issue Si4mentioning

confidence: 99%

Physics and applications of superhydrophobic and superhydrophilic surfaces and coatings

Drelich

Marmur

2014

Surface Innovations

Self Cite

156

View full text Add to dashboard Cite

The terms superhydrophobicity and superhydrophilicity were introduced not very long ago, in 1996 and 2000, respectively.The former is used to describe exceptionally weak and the latter used to indicate strong interactions of materials and IntroductionAfter more than two centuries of research, capillarity and wetting phenomena still remain popular topics of investigation in many modern surface chemistry laboratories. Curiosity and fascination with rain droplets splashing in a puddle, water droplets decorating flowers, leaves of plants and fruits after rain or watering and colorful soap bubbles shaped at the end of wheat straw have never been stronger and go beyond scientific laboratories. Colorful images of liquid droplets and puddles, illustrating their behavior on a variety of surfaces, thrive in professional journals, popular magazines and Internet. However, terms such as wetting, spreading and contact angle are still puzzling to the layman and beginner researcher. To facilitate

show abstract

Section: Surface Innovations Volume 2 Issue Si4mentioning

confidence: 99%

Physics and applications of superhydrophobic and superhydrophilic surfaces and coatings

Drelich

Marmur

2014

Surface Innovations

Self Cite

156

View full text Add to dashboard Cite

show abstract

“…A drop gently deposited on the texture often is in the Cassie levitating state (33, 36), whereas after an impact it can get impaled in the so-called Wenzel state (37). Most generally, one of the states is metastable (33,34,38), with an energy barrier large enough to prevent spontaneous transition to the other state (39,40). Metastability is beneficial for achieving relatively robust slippery Cassie states (1, 2, 32, 41-44), but detrimental in strongly pinned sticky Wenzel situations (33, 45).…”

mentioning

confidence: 99%

Monostable superrepellent materials

Quéré

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

104

View full text Add to dashboard Cite

Superrepellency is an extreme situation where liquids stay at the tops of rough surfaces, in the so-called Cassie state. Owing to the dramatic reduction of solid/liquid contact, such states lead to many applications, such as antifouling, droplet manipulation, hydrodynamic slip, and self-cleaning. However, superrepellency is often destroyed by impalement transitions triggered by environmental disturbances whereas inverse transitions are not observed without energy input. Here we show through controlled experiments the existence of a "monostable" region in the phase space of surface chemistry and roughness, where transitions from Cassie to (impaled) Wenzel states become spontaneously reversible. We establish the condition for observing monostability, which might guide further design and engineering of robust superrepellent materials.repellency | Cassie state | monostability | interfaces | dewetting W ater repellency describes the ability of materials to repel water and make it flow with negligible friction and adhesion, compared with usual situations. It is achieved by combining chemical hydrophobicity with micro-and/or nanotextures (1, 2). Water meeting such materials remains at the textures' tops, which generates a composite interface made of hydrophobic solid and air trapped inside the textures (Cassie state) (3). As a consequence, water hardly contacts these solids on which its dynamical behaviors are spectacular (4-7). Repellency also holds if the liquid has a higher surface tension than water (salty water, mercury); using special texture designs, it can even be extended to liquids with smaller surface tension (8), and/or to water at small scale (such as dew) (9, 10), so it was proposed (11) to call such materials "superhygrophobic," from the Greek "hygros" meaning humid.Repellent materials are classically found in nature, in particular at the surface of many plants and insects, two situations where the control of water is crucial for surviving (1, 12). It was reported that these natural surfaces often (yet not always) exhibit dual structures, with microbumps on the scale of 10-100 μm coated by nanostructures of typically 100 nm (1). This results in an amplification of static (13-17) and dynamical (18) repellency, because we can then expect the generation of composite solid/air interfaces at different scales--where we mean by amplification an improved nonwettability (13-15, 17) and a smaller adhesion (16,18,19), two factors that contribute to the liquid mobility.This field of research has been very active for about 20 years, with theoretical, experimental, and computational viewpoints. Researchers discussed the surface energy of materials having different kinds of structures (20-23), various adhesion properties (24-26), diverse geometries of solid-liquid-vapor contact lines (27, 28), or flow interactions between the liquid and its substrate (29-32). In many studies, model hydrophobic textures (such as lines or pillars) were considered, and wetting was found to be usually "bistable": Depending on the history o...

show abstract

“…The triggering mechanisms for the transition are still debated in literature [18][19][20]. Theoretical analysis [18,21,22] has shown that the state with a smaller contact angle corresponds to a lower energy level. The presence of energy barriers between the two states may prevent a spontaneous transition and triggering is needed to induce the transition from the higher energy state to the lower energy state [9,10,20,23,24].…”

Section: Cassie-baxter State Wenzel Statementioning

confidence: 99%

“…A few examples of frequently used design techniques [3,[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] are listed in figure 1. Detailed descriptions of these and many more processes are given in a review by Geissler and Xia [26].…”

Section: Introduction On Patterningmentioning

confidence: 99%

Micro-patterned interfaces affecting transport through and along membranes

Peters

View full text Add to dashboard Cite

show abstract

The Lotus Effect: Superhydrophobicity and Metastability

Cited by 1,034 publications

References 24 publications

Physics and applications of superhydrophobic and superhydrophilic surfaces and coatings

Physics and applications of superhydrophobic and superhydrophilic surfaces and coatings

Monostable superrepellent materials

Micro-patterned interfaces affecting transport through and along membranes

Contact Info

Product

Resources

About