The pagoda instability (PI) on soluble fibers

Abstract

This paper presents a new kind of instability when inserting a soluble fiber into liquid. After wetting and dissolving the fiber by the liquid, the moving contact line (MCL) spontaneously loses stability. Because the sculpted shape from fiber looks like a Chinese pagoda, we name this instability as pagoda instability (PI). Coupling of dissolution and wetting leads to other special phenomena, i.e. dissolving-induced jet flow, and optimizes the fiber shape, etc. We propose a criterion of PI and show the competition between interface energy and chemical potential deduce the MCL motion and PI. A phase diagram is used to summary the final shapes of fibers. By conducting atomic force microscope (AFM) measurement, we find the fiber with optimized-shape has the characteristics of low adhesion force. Using the optimized-fiber can decrease the 70% influence of capillary force for AFM measurement in humid environment.