Drops retracting while forming a rim

Rafael Tadmor, Victor Multanen, Yotam Stern, Yarden Ben Yakir

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Hypothesis: Surfactant laden droplets may spread faster on a substrate and, subsequently, retract (spontaneously reversing the drop's direction). We hypothesize that this Marmur-Lelah type retraction can be explained by a de Gennes-type triple line fluctuation expression that is modified to represent our anisotropic surfactant adsorption. This explanation requires that the retraction originates inner to the triple line (not at the triple line itself). Experiments: Drops of oil with surfactant (mainly tetradecane with octadecylamine) were allowed to spread on freshly cleaved mica surfaces at various concentrations and recorded with a high-speed camera. Findings: At low concentrations, the subsequent retraction left a rim of liquid at the triple line location of maximal spreading whose thickness was inversely related to the surfactant concentration. This indeed agrees with de Gennes’ triple line fluctuation expression that is modified to fit the anisotropic adsorption of the surfactant during the spreading period, which induces a solid–liquid interfacial energy gradient. According to this explanation, the rim may exist also at high surfactant solution concentrations, however, there can be a limit at which the surfactant solution concentration is so high that the rim's thickness is practically zero.

Original languageEnglish
Pages (from-to)496-503
Number of pages8
JournalJournal of Colloid and Interface Science
StatePublished - 1 Jan 2021


  • Adsorption
  • Fluctuations
  • Spreading
  • Surfactant

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry


Dive into the research topics of 'Drops retracting while forming a rim'. Together they form a unique fingerprint.

Cite this