Sommaire:

Contact angle hysteresis (CAH), where the motion of a contact line between a liquid interface and a solid substrate is pinned by the physical roughness and/or chemical inhomogeneity on the solid surface, is an outstanding problem in interfacial dynamics and has been with us for many years. Despite of numerous efforts, one still has a poor understanding of CAH on many ambient solid surfaces of interest. The study of CAH is of fundamental interest for our general understanding of a common class of problems involving elastic dynamics in random force fields and also has immense practical applications in tertiary oil recovery, drag reduction, advanced materials and microfluidics. In this talk I will present our recent experimental efforts in developing an atomic force microscope (AFM) based hanging fiber probe for the study of contact line dissipation and pinning-depinning dynamics [1-3]. With this new technique, AFM is used as a force sensor to measure the speed-dependent capillary force hysteresis and relaxation of a moving contact line formed on a long vertical glass fiber of a few microns in diameter with one end glued onto a AFM cantilever and the other end in contact with a liquid-air interface. Applications of this technique to the study of contact line dissipation and wetting dynamics will be discussed.

*Work done in collaboration with Dongshi Guan, Yongjian Wang, Elisabeth Charlaix and was supported by the Research Grants Council of Hong Kong SAR.

[1] “Asymmetric and speed-dependent capillary force hysteresis and relaxation of a suddenly stopped moving contact line,” D.-S. Guan, Y.-J. Wang, E. Charlaix and P. Tong, Phys. Rev. Lett. 116, 066102 (2016).

[2] “Understanding of Contact Angle Hysteresis on an Ambient Solid Surface,” Y. J. Wang, S. Guo, H.-Y. Chen, and P. Tong, Phys. Rev. E 93, 052802 (2016).

[3] “Simultaneous observation of asymmetric speed-dependent contact force hysteresis and slow relaxation of a suddenly stopped moving contact line,” D.-S. Guan, Y.-J. Wang, E. Charlaix and P. Tong, Phys. Rev. E 94, 042802 (2016).

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Pour plus d'informations, merci de contacter Truzzolillo D.