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

An azide-functionalized shape memory elastomer, poly(octylene diazoadipate-co-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 T-m to return to the primary shape, uniaxial wrinkles perpendicular to the direction of strain with sizes of 27-33 mu m appear in addition to micrometer-sized features formed on the temporary shape after grafting. Swelling equilibration time (t(1)) and grafting reaction time (t(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.