Using bulk convection in a microtensiometer to approach kinetic-limited surfactant dynamics at fluid-fluid interfaces

Nicolas J. Alvarez, Douglas R. Vogus, Lynn M. Walker, Shelley L. Anna

Research output: Contribution to journalArticlepeer-review

64 Scopus citations

Abstract

The impact of transport of surfactants to fluid-fluid interfaces is complex to assess and model, as many processes are in the regime where kinetics, diffusion and convection are comparable. Using the principle that the timescale for diffusion decreases with increasing curvature, we previously developed a microtensiometer to accurately measure fundamental transport coefficients via dynamic surface tension at spherical microscale liquid-fluid interfaces. In the present study, we use a low Reynolds number flow in the bulk solution to further increase the rate of diffusion. Dynamic surface tension is measured as a function of Peclet number and the results are compared with a simplified convection-diffusion model. Although a transition from diffusion to kinetic-limited transport is not observed experimentally for the surfactants considered, lower bounds on the adsorption and desorption rate constants are determined that are much larger than previously reported rate constants. The results show that the details of the flow field do not need to be controlled as long as the local Reynolds number is low. Aside from other pragmatic advantages, this experimental tool and analysis allows the governing mechanisms of surfactant transport at liquid-fluid interfaces to be quantified using flow near the interface to decrease the length scale for diffusion, separating the relevant timescales.

Original languageEnglish (US)
Pages (from-to)183-191
Number of pages9
JournalJournal of Colloid And Interface Science
Volume372
Issue number1
DOIs
StatePublished - Apr 15 2012
Externally publishedYes

Bibliographical note

Funding Information:
Partial funding for this work was provided by the NSF under Grants Nos. CBET-0730727 and CBET-1033814. NJA appreciates the funding provided by an NSF Graduate Research Fellowship. Support for DRV is acknowledged from the REU NSF Site Program of the NSF under Grant No. DMR-1005076.

Keywords

  • Adsorption kinetic barriers
  • Convection
  • Diffusion
  • Dynamic surface tension
  • Surfactant transport

Fingerprint

Dive into the research topics of 'Using bulk convection in a microtensiometer to approach kinetic-limited surfactant dynamics at fluid-fluid interfaces'. Together they form a unique fingerprint.

Cite this