Comment on How Wenzel and Cassie Were Wrong by Gao and McCarthy

Panchagnula, Mahesh V.; Vedantam, Srikanth

doi:10.1021/la7022117

Cited by 104 publications

(93 citation statements)

References 11 publications

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“…The configurations of protrusions in the hydrophobicity play a determining role where wetting behaviour is influenced by non-homogeneous and disordered structuring in the three dimensions. The applicability of the Wenzel and Cassie-Baxter approximations has in recent times come into question (Nosonovsky, 2007a;Gao and McCarthy, 2007;Panchagnula and Vedantam, 2007;McHale, 2007;Bormashenko, 2008;Goodwyn et al, 2008;Marmur and Bittoun, 2009). Indeed on the surfaces in our study, local conditions at the contact line, and global considerations in relation to the solid-liquid interfacial area may be influenced to varying extents by the surface irregularities.…”

Section: Relationship Between Microstructure and Wetting Propertiesmentioning

confidence: 75%

Wetting properties on nanostructured surfaces of cicada wings

Sun

Watson

Zheng

et al. 2009

Journal of Experimental Biology

192

153

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SUMMARYThis study has investigated the wettability of forewings of 15 species of cicadas, with distinctly different wetting properties related to their nanostructures. The wing surfaces exhibited hydrophilic or weak to strong hydrophobic properties with contact angles ranging from 76.8 deg. to 146.0 deg. The nanostructures (protrusions), observed using environmental scanning electron microscopy (ESEM), were classified into four types according to the patterning, diameter (82-148 nm), spacing (44-117 nm) and height (159-446 nm). Surface analysis by X-ray photoelectron spectroscopy (XPS) showed significant differences in wing membrane chemistry. Thus, wetting properties at the macroscopic scale were dependent on slight differences in nanoscale architecture and composition of the wax layer. This investigation offers insights into the diversity of nanostructuring and how subtle small-scale changes may facilitate large changes in wettability. Supplementary material available online at

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Section: Relationship Between Microstructure and Wetting Propertiesmentioning

confidence: 75%

Wetting properties on nanostructured surfaces of cicada wings

Sun

Watson

Zheng

et al. 2009

Journal of Experimental Biology

192

153

View full text Add to dashboard Cite

show abstract

“…In contrast, an inappropriate choice of surface area fractions for this case would be based on the total geometric surface area fractions under the drop, given by f PFA = (area of etched PFA)/(total solid-liquid interfacial area) and f ePFA = 1 − f PFA [35]. The disagreement between Cassie theory and Extrand's [31] experiment arises from an incorrect choice of surface area fractions [50]. These observations are embodied in the phase field simulations since the evolution of the phase field variable occurs at the three-phase contact line following an energetically favorable path.…”

Section: Resultsmentioning

confidence: 99%

Constitutive modeling of contact angle hysteresis

Vedantam

Panchagnula

2008

Journal of Colloid and Interface Science

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“…Finally, h 1 and h 2 refer to the equilibrium contact angles on solid (=h E ) and air (=180°) phases, respectively [4,6]. The CB relation is widely used [7]; however, there has been a long-standing debate in the literature regarding the range of applicability, as well as the accuracy of the CB relationship [5,[7][8][9][10][11][12][13][14][15][16][17][18][19]. This dispute stems from the fact that a range of contact angles h * can be established on a given composite interface as a droplet advances or recedes.…”

Section: Introductionmentioning

confidence: 99%