title: Flattening of a patterned compliant solid by surface stress.
abstract: We measured the shape change of periodic ridge surface profiles in gelatin organogels resulting from deformation driven by their solid-vapor surface stress. A gelatin organogel was molded onto poly-dimethylsiloxane (PDMS) masters having ridge heights of 1.7 and 2.7 μm and several periodicities. Gel replicas were found to have a shape deformed significantly compared to their PDMS master. Systematically larger deformations in gels were measured for lower elastic moduli. Measuring the elastic modulus independently, we estimate a surface stress of 107 ± 7 mN m(-1) for the organogels in solvent composed of 70 wt% glycerol and 30 wt% water. Shape changes are in agreement with a small strain linear elastic theory. We also measured the deformation of deeper ridges (with height 13 μm), and analysed the resulting large surface strains using finite element analysis.
authors.affiliation: Department of Chemical Engineering, Lehigh University, Bethlehem, PA 18015, USA. anj6@lehigh.edu.
authors.forename: Dadhichi
authors.initials: D
authors.lastname: Paretkar
authors.forename: Xuejuan
authors.initials: X
authors.lastname: Xu
authors.forename: Chung-Yuen
authors.initials: CY
authors.lastname: Hui
authors.forename: Anand
authors.initials: A
authors.lastname: Jagota