Abstract
Rose petal mimetic surfaces with ultrahigh water pinning forces have been fabricated via nanoimprinting process onto three different polymer films. Water pinning forces ranging from 104 to 690 mu N are obtained on free-standing polycarbonate films with imprinted nanostructures. Through a systematic variation of the surface structures, this study provides experimental evidence that an ultrahigh water pinning force can be achieved by combining two surface topographical designs: (1) conical- or parabolic-shaped nanoprotrusions and (2) isotropic and continuous nano-protrusions. These design criteria ensure that a continuous solid liquid contact line is achieved and provide a rule-of-thumb to engineer surfaces with tunable water pinning forces. The ultrahigh water pinning film is further demonstrated to mitigate the "coffee ring" effect, a phenomenon associated with nonuniform deposition from a drying solute-laden liquid droplet.