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Variations on the coffee ring effect

Event Details

Event Dates: 

Thursday, December 11, 2014 - 12:00pm

Seminar Location: 

  • JILA X317

Speaker Name(s): 

Arjun Yodh

Speaker Affiliation(s): 

University of Pennsylvania
Seminar Type/Subject

Scientific Seminar Type: 

  • Condensed Matter Seminar

Event Details & Abstract: 

I will discuss the famous coffee ring effect, and will illustrate how one can make the effect “disappear” by replacing colloidal spheres with ellipsoids in the drying droplet [1]. The role of particle shape can be understood, at least partially, to be a result of capillary interactions which are comparatively strong for ellipsoids compared to spheres [2].  I will then discuss evaporation of colloidal droplets in confined geometries (i.e., rather than the sessile drops), which is also influenced by the rigidity of monolayer particle membranes (and the effect of particle shape on this rigidity), and I will describe measurements of particle growth profiles at the drop edge which are sometimes described by KPZ models, depending on capillary interaction strength [3]. Lastly, if time is sufficient, I will show similar drying processes in colloidal droplets with surfactants [4]. 

[1]   Yunker, P.J., Still, T., Lohr, M.A., Yodh, A.G., Nature 476, 308-311 (2011).
[2]   Loudet, J.C., Alsayed, A.M., Zhang, J., Yodh, A.G., Phys. Rev. Lett. 94, 018301 (2005); Loudet J.C., Yodh A.G., Pouligny B., Phys. Rev. Lett. 97, 018304 (2006).
[3]   Yunker, P.J., Gratale, M., Lohr, M.A., Still, T., Lubensky, T.C., Yodh, A.G., Phys. Rev. Lett. 108, 228303 (2012); Yunker, P.J., Lohr, M.A., Still, T., Borodin, A., Durian, D.J., Yodh, A.G., Phys. Rev. Lett. 110, 035501 (2013); Yunker, P.J., Durian, D.J, Yodh, A.G., Physics Today 66, 60 (2013). 
[4]   Still, T., Yunker, P.J., Yodh, A.G., Langmuir 28, 4984 (2012).