Internal flow in polymer solution droplets deposited on a lyophobic surface during a receding process

Masayuki Kaneda, Kentarou Hyakuta, Yuu Takao, Hirotaka Ishizuka, Jun Fukai

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

When a polymer solution droplet is deposited on a lyophobic surface, the contact line is moved back to some degree and subsequently pinned. An experimental setup is constructed to investigate not only the receding process but also an internal flow of polystyrene - acetophenoneand - anisole solutions. As a result, the time variation of the evaporation rate per unit area during receding does not strongly depend on the initial solute concentration. The average solute concentration at the pinning of the contact line increases as the initial solute concentration increases. A convective circulation flow that is upward at the axis of symmetry is observed. This flow pattern is different from those of pure liquids such as water, acetone, benzene, and so forth, which have been previously reported. Furthermore, the observed flow is enhanced as the initial solute concentration increases, contrary to an increase in the fluid viscosity. To resolve these discrepancies, the mechanism of the flow is numerically investigated using a hemispherical droplet model considering the density and surface tension distributions. The numerical results demonstrate that the circulation flow that is experimentally observed is actually caused. It is also found that the solutal Rayleigh effect initially induces the internal flow, and subsequently the solutal Marangoni effect dominates the flow. Both effects are enhanced as the initial concentration increases because of the evaporative mass balance at the free surface.

Original languageEnglish
Pages (from-to)9102-9109
Number of pages8
JournalLangmuir
Volume24
Issue number16
DOIs
Publication statusPublished - Aug 19 2008

Fingerprint

internal flow
Polymer solutions
solutes
Polystyrenes
polymers
Acetone
Benzene
Flow patterns
Contacts (fluid mechanics)
Surface tension
Evaporation
Viscosity
Fluids
Water
Liquids
anisole
evaporation rate
mass balance
acetone
polystyrene

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

Cite this

Internal flow in polymer solution droplets deposited on a lyophobic surface during a receding process. / Kaneda, Masayuki; Hyakuta, Kentarou; Takao, Yuu; Ishizuka, Hirotaka; Fukai, Jun.

In: Langmuir, Vol. 24, No. 16, 19.08.2008, p. 9102-9109.

Research output: Contribution to journalArticle

Kaneda, Masayuki ; Hyakuta, Kentarou ; Takao, Yuu ; Ishizuka, Hirotaka ; Fukai, Jun. / Internal flow in polymer solution droplets deposited on a lyophobic surface during a receding process. In: Langmuir. 2008 ; Vol. 24, No. 16. pp. 9102-9109.
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