Quasi-static motion of microparticles at the depinning contact line of an evaporating droplet on PDMS surface |
| |
Authors: | Ying-Song Yu Xue-Lian Xia Xu Zheng Xianfu Huang Jin-Zhi Zhou |
| |
Institution: | 1.Department of Mechanics, School of Civil Architecture and Environment,Hubei University of Technology,Wuhan,China;2.State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics,Chinese Academy of Sciences,Beijing,China;3.School of Engineering Science,University of Chinese Academy of Sciences,Beijing,China |
| |
Abstract: | In this paper, evaporation of sessile water droplets containing fluorescent polystyrene (PS) microparticles on polydimethylsiloxane (PDMS) surfaces with different curing ratios was studied experimentally using laser confocal microscopy. At the beginning, there were some microparticles located at the contact line and some microparticles moved towards the line. Due to contact angle hysteresis, at first both the contact line and the microparticles were pinned. With the depinning contact line, the microparticles moved together spontaneously. Using the software ImageJ, the location of contact lines at different time were acquired and the circle centers and radii of the contact lines were obtained via the least square method. Then the average distance of two neighbor contact lines at a certain time interval was obtained to characterize the motion of the contact line. Fitting the distance-time curve at the depinning contact line stage with polynomials and differentiating the polynomials with time, we obtained the velocity and acceleration of both the contact line and the microparticles located at the line. The velocity and the maximum acceleration were, respectively, of the orders of 1 μm/s and 20-200 nm/s2, indicating that the motion of the microparticles located at the depinning contact line was quasi-static. Finally, we presented a theoretical model to describe the quasi-static process, which may help in understanding both self-pinning and depinning of microparticles. |
| |
Keywords: | |
本文献已被 CNKI SpringerLink 等数据库收录! |
|