Measurement of contact-line dissipation in a nanometer-thin soap film

Guo, Shuo; Lee, Chun Huen; Sheng, Ping; Tong, Penger

doi:10.1103/physreve.91.012404

Cited by 7 publications

(7 citation statements)

References 35 publications

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“…The measured values of k s for the seven liquid-air interfaces used in the experiment are given in Table I. The attempt frequency K 0 is estimated as K 0 2D 0 /λ 2 = 2k B T /(λ 2 ξ ), where D 0 = k B T /ξ is the diffusion coefficient of the CL with ξ = (1.1 ± 0.3)ηλ being its friction coefficient [42,43]. Here η is the viscosity of the liquid.…”

Section: B Rupture Force Spectroscopy Of CL Depinningmentioning

confidence: 99%

Simultaneous observation of asymmetric speed-dependent capillary force hysteresis and slow relaxation of a suddenly stopped moving contact line

et al. 2016

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We report direct atomic-force-microscope measurements of capillary force hysteresis (CFH) and relaxation of a circular moving contact line (CL) formed on a long micron-sized hydrophobic fiber intersecting a liquid-air interface. By using eight different liquid interfaces with varying solid-liquid molecular interactions, we find a universal behavior of the asymmetric speed dependence of CFH and CL relaxation. A unified model based on force-assisted barrier crossing is used to connect the mesoscopic measurements of CFH and CL relaxation with the energy barrier height E_{b} and size λ associated with the surface defects. The experiment demonstrates that the CL pinning (relaxation) and depinning dynamics are closely related and can be described by a common microscopic framework.

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Section: B Rupture Force Spectroscopy Of CL Depinningmentioning

confidence: 99%

Simultaneous observation of asymmetric speed-dependent capillary force hysteresis and slow relaxation of a suddenly stopped moving contact line

et al. 2016

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“…As a sensitive mechanical resonator, the hanging fiber probe can accurately measure a minute change of its viscous damping, when the fiber tip touches a liquid-air interface, at which a circular CL between the liquid interface and fiber surface is formed. In recent experiments [24,25], this "long needle" AFM was fully calibrated and used to measure the friction coefficient of a fluctuating CL. The hanging fiber probe shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Understanding contact angle hysteresis on an ambient solid surface

et al. 2016

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We report a systematic study of contact angle hysteresis (CAH) with direct measurement of the capillary force acting on a contact line formed on the surface of a long glass fiber intersecting a liquid-air interface. The glass fiber of diameter 1-2μm and length 100-200μm is glued onto the front end of a rectangular cantilever beam, which is used for atomic force microscopy. From the measured hysteresis loop of the capillary force for 28 different liquids with varying surface tensions and contact angles, we find a universal behavior of the unbalanced capillary force in the advancing and receding directions and the spring constant of a stretched meniscus by the glass fiber. Measurements of the capillary force and its fluctuations suggest that CAH on an ambient solid surface is caused primarily by two types of coexisting and spatially intertwined defects with opposite natures. The contact line is primarily pinned by the relatively nonwetting (repulsive) defects in the advancing direction and by the relatively wetting (attractive) defects in the receding direction. Based on the experimental observations, we propose a "composite model" of CAH and relevant scaling laws, which explain the basic features of the measured hysteresis force loops.

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“…A critical assumption made to link the MKT prediction to the bulk flow measurements is that the viscous dissipation of the bulk fluid is negligibly small at low speed. It was recently shown [11,12] that the dissipation of the MCL has the same velocity and viscosity dependence as that for the bulk flow but with a smaller numerical prefactor. As a result, many dynamic measurements of the CL contain significant contributions from the bulk flow, making the comparison between the MKT and experimental results inaccurate [12,13].…”

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confidence: 96%

Asymmetric and Speed-Dependent Capillary Force Hysteresis and Relaxation of a Suddenly Stopped Moving Contact Line

et al. 2016

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We report on direct atomic-force-microscope measurements of capillary force hysteresis (CFH) and relaxation of a circular moving contact line (CL) formed on a long micron-sized hydrophobic fiber intersecting a water-air interface. The measured CFH and CL relaxation show a strong asymmetric speed dependence in the advancing and receding directions. A unified model based on force-assisted barrier crossing is utilized to find the underlying energy barrier Eb and size λ associated with the defects on the fiber surface. The experiment demonstrates that the pinning (relaxation) and depinning dynamics of the CL can be described by a common microscopic framework, and the advancing and receding CLs are influenced by two different sets of relatively wetting and nonwetting defects on the fiber surface.

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Measurement of contact-line dissipation in a nanometer-thin soap film

Cited by 7 publications

References 35 publications

Simultaneous observation of asymmetric speed-dependent capillary force hysteresis and slow relaxation of a suddenly stopped moving contact line

Simultaneous observation of asymmetric speed-dependent capillary force hysteresis and slow relaxation of a suddenly stopped moving contact line

Understanding contact angle hysteresis on an ambient solid surface

Asymmetric and Speed-Dependent Capillary Force Hysteresis and Relaxation of a Suddenly Stopped Moving Contact Line

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