1D Capillary Bending of a Thin, Floating Polymer Film

Interest in the application of capillary origami has been expanding to many different areas of science and technology. However, insight into the basic physics of the process behind how a thin film is pulled to cover a droplet of fluid is still lacking. For example, the role of the substrate is largely ignored, but can easily arrest the wrapping process. The process can also be stopped by the friction and jamming which occurs due to self contact. Our work seeks to further the basic understanding with a one-dimensional experiment that both avoids bot self contact and uncontrolled substrate interactions. Specifically, we create a long, flat triple line on a film which rests on a fluid bath (modeled as a Winkler foundation). The capillary force acts on the film in a one-dimensional manner, pulling perpendicular to the triple line, without creating wrinkles or folds in the floating film. The experiment allows the system to reach an equilibrium between the capillary forces, the bending of the film, and the displacement of the substrate. A model of the system allows the further characterization of the effects of each of these forces on the shape of the bend produced in the supported film.