Moving Contact Line Instability on Soluble Fibers

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 of the fiber looks like a Chinese pagoda, this instability is named as the pagoda instability (PI). The coupling of dissolution and wetting leads to other special phenomena, i.e., dissolving-induced jet flow, and optimizes the fiber shape, etc. A criterion of PI is proposed and the competition between the interfacial energy and chemical potential to deduce the MCL motion and PI is shown. A phase diagram is used to summarize the final shapes of the fibers. By conducting atomic force microscopy (AFM) measurements, it is found that fibers with optimized shapes have a low adhesion force. Using the optimized fiber can decrease the influence of the capillary force during AFM measurements in humid environments by 70%.

Automated summary

This paper presents a new type of instability called the pagoda instability (PI) that occurs when inserting a soluble fiber into a liquid. The coupling of dissolution and wetting leads to special phenomena and the final shapes of the fibers are summarized using a phase diagram. The use of optimized fibers can reduce the influence of capillary force during atomic force microscopy measurements in humid environments by 70%.