Grafting Poly(OEGMA) Brushes from a Shape Memory Elastomer and Subsequent Wrinkling Behavior

Abstract

An azide-functionalized shape memory elastomer, poly­(octylene diazoadipate-<i>co</i>-octylene adipate), has been grafted with poly­(oligoethylene glycol) methacrylate (poly­(OEGMA)) brushes via aqueous ARGET (activators regenerated by electron transfer) ATRP. Sequential swelling of the substrate followed by a grafting-from reaction yielded an incompressible brush layer on the shape-memory substrate. Upon heating the substrate above the <i>T</i>_m to return to the primary shape, uniaxial wrinkles perpendicular to the direction of strain with sizes of 27–33 μm appear in addition to micrometer-sized features formed on the temporary shape after grafting. Swelling equilibration time (<i>t</i>₁) and grafting reaction time (<i>t</i>₂) were varied to control wrinkle formation and size. In this manner, we were able to create unique, anisotropic hierarchical surface structures with different length scales and patterns