Colloquium 145

Title: Dynamics of Soft Matter at a Three-phase Contact Line

Speaker: Penger Tong,  Department of Physics, Hong Kong University of Science and Technology, Hong Kong 

Location:  Room 111, Physics Building

Time: 15:00-16:00, Wed, Apr.16 2014

Abstract:
The study of the dynamics at a three-phase contact line between a liquid-air interface and a solid surface 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 wetting dynamics [1,2]. With this new technique, AFM is used as a force sensor to measure the viscous dissipation of a fluctuating contact line and capillary forces acting on a micron-sized vertical glass fiber 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.
[1] “Development of an atomic-force-microscope-based hanging-fiber rheometer for interfacial microrheology,” X.-M Xiong, S. Guo, Z.-L. Xu, P. Sheng, P. Tong, Phys. Rev. E 80, 061604 (2009).
[2] “Direct measurement of friction of a fluctuating contact line,” S. Guo, M. Gao, X. Xiong, Y. J. Wang, X.-P. Wang, P. Sheng and P. Tong, Phys. Rev. Lett. 111, 026101 (2013).
Work was supported by the Research Grants Council of Hong Kong SAR.

Biography:

EDUCATION
1984-1988: Ph.D. in Physics, University of Pittsburgh, USA.
1983-1984: M.Sc. in Physics, University of Pittsburgh, USA.
1978-1982: B.Sc. in Physics, Northeastern University, Shenyang, China.
PROFESSIONAL EXPERIENCE
2011-present: Associate Dean (Research) of School of Science, Hong Kong U. of Science & Technology.
2011-present: Chair Professor of Physics, Hong Kong University of Science & Technology, Hong Kong.
2003-2011: Professor of Physics, Hong Kong University of Science & Technology, Hong Kong.
2001 (sabbatical leave): Visiting Scientist of Applied Physics, Harvard University, USA.
1999-2002: Professor of Physics, Oklahoma State University, USA.
1995-1999: Associate Professor of Physics, Oklahoma State University, USA.
1990-1995: Assistant Professor of Physics, Oklahoma State University, USA.
1988-1990, Postdoctoral Research Associate, Exxon Research & Engineering Company, New Jersey, USA.