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Wetting and evaporation behaviors of water–ethanol sessile drops on PTFE surfaces
Author(s) -
Shi Laixin,
Shen Ping,
Zhang Dan,
Lin Qiaoli,
Jiang Qichuan
Publication year - 2009
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.3123
Subject(s) - wetting , contact angle , sessile drop technique , drop (telecommunication) , evaporation , wetting transition , materials science , composite material , chemistry , thermodynamics , telecommunications , physics , computer science
The wetting and evaporation behaviors of water–ethanol mixtures on polished poly(tetrafluoroethylene) (PTFE) surfaces were studied with an emphasis on the influence of concentration. Three representative stages: (i) constant contact diameter with decreasing contact angle and drop height; (ii) increase in contact angle and drop height with decreasing contact diameter; and (iii) simultaneous decrease in contact angle, drop height, and contact diameter, were identified in the wetting process under evaporation. In the initial stage, with increasing ethanol concentration, the wetting and evaporating behaviors of the mixture drops are close to those of pure ethanol, while in the final stage they are close to those of pure water, regardless of the concentration. The most significant difference between the pure substance and mixture drops is in the intermediate stage due to the different controlling mechanisms behind the de‐pinning phenomenon. Moreover, the concrete wetting behavior is dependent on the composition of the mixture drops. For an evaporating sessile drop, the wetting should be evaluated using the combined parameters of contact angle, drop height, and contact diameter. Six representative modes are proposed to describe the wetting behaviors of the water–ethanol sessile drops on the PTFE surfaces under evaporation. Copyright © 2009 John Wiley & Sons, Ltd.