| Issue |
EPL
Volume 83, Number 3, August 2008
|
|
|---|---|---|
| Article Number | 34005 | |
| Number of page(s) | 5 | |
| Section | Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics | |
| DOI | https://doi.org/10.1209/0295-5075/83/34005 | |
| Published online | 23 July 2008 | |
Advancing-drying droplets of polymer solutions: Local increase of the viscosity at the contact line
PPMD, ESPCI, UMR 7615 - 10 rue Vauquelin, 75005 Paris, France, EU
Corresponding author: cecile.monteux@espci.fr
Received:
17
January
2008
Accepted:
16
June
2008
We present experimental results concerning the advancing motion of drops of
polymer solutions in the presence of controlled evaporation. We find that at
high advancing velocities the classical Cox-Voinov law is verified, 
the
advancing contact angle varies linearly with the capillary number. Below a
critical velocity the contact angle increases as the advancing velocity is
reduced. These results can be explained by taking into account the divergence of the rate of evaporation close to the contact line leading to
an accumulation of polymer close to the edge of the drop. The induced local
increase of the viscosity explains the increase of the contact angle. We
show that the accumulation of polymer over a few nanometers is sufficient to
slow down the contact line.
PACS: 47.55.np – Contact lines / 47.57.Ng – Polymers and polymer solutions / 47.55.pf – Marangoni convection
© EPLA, 2008
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