title: Programming Tilting Angles in Shape Memory Polymer Janus Pillar Arrays with Unidirectional Wetting against the Tilting Direction.
abstract: By coating a thin layer of metal, including gold and gold-palladium alloy, of different thickness on the deformed shape memory polymer (SMP) pillars, we manipulate the degree of recovery of the SMP pillars. Pillars of different tilting angles were obtained as a result of balancing the strain recovery energy of the SMP pillars that favor the original straight state and the elastic energy of the metal layers that prefer the bent state. With this selective coating of a metal layer on the tilted pillars, we report a unique anisotropic liquid spreading behavior, where the water droplet is fully pinned in the direction of pillar tilting but advances in the reverse direction. This phenomenon is explained by the interplay of the surface chemistry and topography.
authors: Department of Materials Science and Engineering, University of Pennsylvania , 3231 Walnut Street, Philadelphia, Pennsylvania 19104, United States.
authors: Chi-Mon
authors: CM
authors: Chen
authors: Department of Materials Science and Engineering, University of Pennsylvania , 3231 Walnut Street, Philadelphia, Pennsylvania 19104, United States.
authors: Chang-Lung
authors: CL
authors: Chiang
authors: Department of Materials Science and Engineering, University of Pennsylvania , 3231 Walnut Street, Philadelphia, Pennsylvania 19104, United States.
authors: Shu
authors: S
authors: Yang