Water tribology on graphene

N’guessan, Hartmann E.; Leh, Aisha; Cox, Paris; Bahadur, Prashant; Tadmor, Rafael; Patra, Prabir; Vajtai, Róbert; Ajayan, Pulickel M.; Wasnik, Priyanka

doi:10.1038/ncomms2247

Cited by 66 publications

(80 citation statements)

References 28 publications

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“…However, the method suffers from the inability to control the normal and lateral forces independently. This is a major drawback because the relationship between these forces can be non-trivial 30,31 . A centrifugal adhesion balance can overcome the force coupling problem, but is more suitable for quasi-static measurements (for example, to study the lateral force required to unpin a droplet) than for dynamic measurements (for example, to investigate energy dissipation and the corresponding dissipative forces as a function of droplet speed).…”

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confidence: 99%

Free-decay and resonant methods for investigating the fundamental limit of superhydrophobicity

et al. 2013

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The recently demonstrated extremely water-repellent surfaces with contact angles close to 180°with nearly zero hysteresis approach the fundamental limit of non-wetting. The measurement of the small but non-zero energy dissipation of a droplet moving on such a surface is not feasible with the contemporary methods, although it would be needed for optimized technological applications related to dirt repellency, microfluidics and functional surfaces. Here we show that magnetically controlled freely decaying and resonant oscillations of water droplets doped with superparamagnetic nanoparticles allow quantification of the energy dissipation as a function of normal force. Two dissipative forces are identified at a precision of B10 nN, one related to contact angle hysteresis near the three-phase contact line and the other to viscous dissipation near the droplet-solid interface. The method is adaptable to common optical goniometers and facilitates systematic and quantitative investigations of dynamical superhydrophobicity, defects and inhomogeneities on extremely superhydrophobic surfaces.

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confidence: 99%

Free-decay and resonant methods for investigating the fundamental limit of superhydrophobicity

et al. 2013

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“…The wear rate of Fig. 12 Effect of time on drop retention force for various systems ((a) and (b)) and image of water drops on graphene (c) [85]. PTFE is reduced by four orders of magnitude due to graphene additives according to a report by Kandanur et al [95].…”

Section: Applicationsmentioning

confidence: 94%

“…A detailed analysis of the molecular structure attributed this result to strain-induced change in the interfacial potential energy barrier and the commensurate structure between the graphene walls and the first water layer. In addition to theoretical works, a pioneering experiment done by N'guessan et al probed water tribology on graphene [85]. They found that the lateral force required to slide a water drop on a graphene surface is independent of the resting time of the drop, contrary to classical experiments (Fig.…”

Section: Frictional Interaction Between Liquid and 2d Materialsmentioning

confidence: 99%

Friction of low-dimensional nanomaterial systems

et al. 2014

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When material dimensions are reduced to the nanoscale, exceptional physical mechanics properties can be obtained that differ significantly from the corresponding bulk materials. Here we review the physical mechanics of the friction of low-dimensional nanomaterials, including zero-dimensional nanoparticles, onedimensional multiwalled nanotubes and nanowires, and two-dimensional nanomaterials-such as graphene, hexagonal boron nitride (h-BN), and transition-metal dichalcogenides-as well as topological insulators. Nanoparticles between solid surfaces can serve as rolling and sliding lubrication, while the interlayer friction of multiwalled nanotubes can be ultralow or significantly high and sensitive to interwall spacing and chirality matching, as well as the tube materials. The interwall friction can be several orders of magnitude higher in binary polarized h-BN tubes than in carbon nanotubes mainly because of wall buckling. Furthermore, current extensive studies on two-dimensional nanomaterials are comprehensively reviewed herein. In contrast to their bulk materials that serve as traditional dry lubricants (e.g., graphite, bulk h-BN, and MoS 2 ), large-area highquality monolayered two-dimensional nanomaterials can serve as single-atom-thick coatings that minimize friction and wear. In addition, by appropriately tuning the surface properties, these materials have shown great promise for creating energy-efficient self-powered electro-opto-magneto-mechanical nanosystems. State-of-theart experimental and theoretical methods to characterize friction in nanomaterials are also introduced.

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“…In our group it has been reported that placing micro sized sessile water ''satellite drops'' around a central water drop produces effective evaporation suppression of the central drop [38,39], nevertheless, a detailed study on this effect is performed here for the first time.…”

Section: Introductionmentioning

confidence: 94%

Controlling arbitrary humidity without convection

Wasnik

N’guessan

Tadmor

2015

Journal of Colloid and Interface Science

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In this paper we show a way that allows for the first time to induce arbitrary humidity of desired value for systems without convective flow. To enable this novelty we utilize a semi-closed environment in which evaporation is not completely suppressed. In this case, the evaporation rate is determined both by the outer (open) humidity and by the inner (semi-closed) geometry including the size/shape of the evaporating medium and the size/shape of the semi-closure. We show how such systems can be used to induce desired humidity conditions. We consider water droplet placed on a solid surface and study its evaporation when it is surrounded by other drops, hereon "satellite" drops and covered by a semi-closed hemisphere. The main drop's evaporation rate is proportional to its height, in agreement with theory. Surprisingly, however, the influence of the satellite drops on the main drop's evaporation suppression is not proportional to the sum of heights of the satellite drops. Instead, it shows proportionality close to the satellite drops' total surface area. The resultant humidity conditions in the semi-closed system can be effectively and accurately induced using different satellite drops combinations.

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Water tribology on graphene

Cited by 66 publications

References 28 publications

Free-decay and resonant methods for investigating the fundamental limit of superhydrophobicity

Free-decay and resonant methods for investigating the fundamental limit of superhydrophobicity

Friction of low-dimensional nanomaterial systems

Controlling arbitrary humidity without convection

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