Spontaneous motion of liquid droplets on soft gel surfaces with non-uniform crosslinking densities液滴在非均匀交联密度软凝胶表面的自发运动

Abstract摘要

This work experimentally investigates spontaneous liquid-droplet motion on soft gels with a crosslinking-density gradient. Millimeter-scale droplets travel along the elastic-modulus gradient and can even climb an inclined surface against gravity when the gradient is sufficiently strong. The experiments show that the driving force is a difference in surface energy created by the spatial variation of crosslinking density, rather than the elastocapillary mechanism that commonly governs smaller droplets. In-situ confocal imaging also captures viscoelastic dissipation associated with the moving wetting ridges near dynamic contact lines. The results establish a route for controlling droplets on soft, dissipative interfaces through material design.

本研究通过实验研究交联密度梯度软凝胶表面液滴的自发运动。毫米尺度液滴会沿弹性模量梯度运动；当梯度足够大时，甚至能够在倾斜表面上逆重力爬升。实验表明，这种驱动力主要来自交联密度空间变化造成的表面能差异，而不是通常控制更小液滴运动的弹毛细机制。原位共聚焦成像还揭示了动态接触线附近移动润湿脊所产生的黏弹性耗散，为通过材料设计控制软耗散界面上的液滴运动提供了新路径。