Universal Deformation of Soft Substrates Near a Contact Line and the Direct Measurement of Solid Surface Stresses
2013 (English)In: Physical Review Letters, ISSN 0031-9007, Vol. 110, no 6, 066103- p.Article in journal (Refereed) Published
Droplets deform soft substrates near their contact lines. Using confocal microscopy, we measure the deformation of silicone gel substrates due to glycerol and fluorinated-oil droplets for a range of droplet radii and substrate thicknesses. For all droplets, the substrate deformation takes a universal shape close to the contact line that depends on liquid composition, but is independent of droplet size and substrate thickness. This shape is determined by a balance of interfacial tensions at the contact line and provides a novel method for direct determination of the surface stresses of soft substrates. Moreover, we measure the change in contact angle with droplet radius and show that Young's law fails for small droplets when their radii approach an elastocapillary length scale. For larger droplets the macroscopic contact angle is constant, consistent with Young's law. DOI: 10.1103/PhysRevLett.110.066103
Place, publisher, year, edition, pages
2013. Vol. 110, no 6, 066103- p.
IdentifiersURN: urn:nbn:se:su:diva-88686DOI: 10.1103/PhysRevLett.110.066103ISI: 000314770600016OAI: oai:DiVA.org:su-88686DiVA: diva2:612997
Yale University; Bateman Interdepartmental Postdoctoral Fellowship; Swedish Research Council; NSF DBI-0619674 2013-03-262013-03-252013-09-12Bibliographically approved