When 3:30 PM - 5:00 PM Apr 10, 2009
Where 1670 CSE
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Harnessing Elastic Instability on Elastomeric PDMS Surfaces

Shu Yang, University of Pennsylvania

Nature provides many examples of intrinsic, bottom-up effects, where instabilities, packing constraints, and simple geometries drive the formation of delicate, detailed, and beautiful patterns. Mechanical instabilities in soft polymers, precipitated by dewetting, swelling, and buckling during the production stage, however, are often viewed as failure mechanisms that can interfere with the performance of devices. 


In my talk, we explore the instabilities in elastomeric poly(dimethyl siloxane) (PDMS) films by imposing external forces, e.g. mechanical strain and solvent swelling, to bilayered PDMS and PDMS membranes, respectively. We demonstrate the formation of various wrinkle patterns and assembly of complex structures with sub-100 nm anisotropic features over cm2 regions in a single step. In each system, we compare the experiments with theoretical modeling to elucidate the mechanisms of elastic instability and to tailor the elastic distortions. By mechanically tune the surface topography, we demonstrate dynamic tuning of wetting and adhesion on PDMS wrinkles. Further, we explore pattern symmetry and pattern-transfer of complex structures to inorganic substrates for potential photonic applications.