Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Polymer Science and Engineering Department, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Nat Mater. 2015 Dec;14(12):1206-9. doi: 10.1038/nmat4397. Epub 2015 Aug 31.
Elastic sheets offer a path to encapsulating a droplet of one fluid in another that is different from that of traditional molecular or particulate surfactants. In wrappings of fluids by sheets of moderate thickness with petals designed to curl into closed shapes, capillarity balances bending forces. Here, we show that, by using much thinner sheets, the constraints of this balance can be lifted to access a regime of high sheet bendability that brings three major advantages: ultrathin sheets automatically achieve optimally efficient shapes that maximize the enclosed volume of liquid for a fixed area of sheet; interfacial energies and mechanical properties of the sheet are irrelevant within this regime, thus allowing for further functionality; and complete coverage of the fluid can be achieved without special sheet designs. We propose and validate a general geometric model that captures the entire range of this new class of wrapped and partially wrapped shapes.
弹性薄片为包裹不同流体提供了一种途径，这与传统的分子或颗粒表面活性剂不同。在由具有花瓣设计的中等厚度薄片包裹的流体中，薄片可以卷曲成封闭形状，通过毛细作用平衡弯曲力。在这里，我们表明，通过使用更薄的薄片，可以解除这种平衡的约束，从而进入一个高薄片柔韧性的状态，这带来了三个主要的优势：超薄薄片自动实现最佳效率形状，最大程度地增加了固定薄片面积内的液体体积；在这个状态下，薄片的界面能和力学性能是无关的，因此可以实现进一步的功能；并且无需特殊的薄片设计即可实现对流体的完全覆盖。我们提出并验证了一个通用的几何模型，该模型捕获了整个新的包裹和部分包裹形状的范围。
