Reversibly\nSwitchable Topography Enabled by Melting\nand Crystallization of Melt-Electrowritten Polymer Fibers

We report the fabrication of topographically structured\nsurfaces\nwith reversibly switchable topography by using melt electrowriting\n(MEW). In particular, MEW was used to produce continuous high aspect\nratio lamellae of semicrystalline polyester urethane with a poly(1,10-decylene\nadipate) soft segment. The switching of topography is achieved by\nthe expansion and contraction of the polymer caused by the melting\nand crystallization of the soft segment that results in the buckling\nof lamellae. In the molten stage, lamellae can be buckled in a certain\ndirection by capillary forces caused by water droplets between two\nlamellae. In addition, the interlamellar distance between neighbors’\nlamellae can be managed by water droplets. Finally, we have demonstrated\nthe possibility of creating electrically conductive surfaces with\nswitchable conductivity achieved by the reversible buckling of the\nlamellae.