Capillary-Induced Wrinkle-to-Fold Transitions Under Biaxial Compression
Capillary-Induced Wrinkle-to-Fold Transitions Under Biaxial Compression
复制标题
双轴压缩下毛细管诱导的皱纹到折叠的转变
DOI：
10.1021/acs.langmuir.1c00347
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发表时间：
2021
期刊：
影响因子：
3.9
通讯作者：
Akihiro Nakatani
中科院分区：
文献类型：
--
作者：
So Nagashima;Akihiro Nakatani
包括附着到软基底的薄的刚性膜的双层系统中的褶皱可以在足够大的压缩下整体地转变成褶皱。这种现象已经被广泛研究，主要是使用单轴压缩系统。然而，在小的双轴压缩下，诱导褶皱表面上的指定位置处的褶皱到折叠的转变仍然是一个挑战。在这项研究中，我们描述了一种方法，使随机取向的皱纹局部演变成褶皱使用水滴。当液滴与由于残余双轴压缩应变而在膜沉积时自发形成的随机褶皱接触时，在液滴边界处立即出现径向延伸的褶皱。在水蒸发时，液滴下方的褶皱也经历转变，留下折叠网络。相比之下，远离放置液滴的地方的表面区域保留褶皱形态。可以通过调节液滴的体积和数量来控制折叠区域。这些转变是通过水的毛细力实现的，毛细力有助于增加局部压缩应变。这种毛细管诱导的褶皱到褶皱的转变提供了一种简单的机制，以在受到小的双轴压缩的膜-基底系统的褶皱表面上的选定位置中形成褶皱，这是用常规方法无法实现的。
Wrinkles in bilayer systems comprising a thin stiff film attached to a soft substrate can globally transition into folds under sufficiently large compression. This phenomenon has been extensively studied primarily using uniaxially compressed systems. However, inducing the wrinkle-to-fold transition at designated locations on a wrinkled surface under small biaxial compression remains a challenge. In this study, we describe a method for causing randomly oriented wrinkles to locally evolve into folds using water droplets. When a droplet comes into contact with the random wrinkles that have spontaneously formed upon film deposition owing to residual biaxial compressive strains, radially extended folds instantaneously emerge at the droplet boundary. Upon water evaporation, the wrinkles beneath the droplet also undergo a transition, leaving a fold network. By contrast, the surface regions distant from where the droplet was placed retain the wrinkle morphology. The folded areas can be controlled by adjusting the volume and number of droplets. These transitions are enabled by the capillary forces of water that help to increase the local compressive strains. This capillary-induced wrinkle-to-fold transition provides a simple mechanism to develop folds in selected locations on wrinkled surfaces of film–substrate systems subject to small biaxial compression, which is unachievable with conventional approaches.