For the first time it is reported that the kapok petal shows a superhydrophobic characteristic with a static water contact angle higher than 150°. Intriguingly, there exist single-scale micro-trichomes and no more nanocrystals on a kapok petal in contrast to most natural superhydrophobic surfaces with hierarchical morphologies, such as the lotus leaf and rose petal. Experimental results show that the kapok petal has an excellent self-cleaning ability either in air or oil. Further scanning electron microscopy characterization demonstrates that the superhydrophobic state is induced by densely distributed microscale trichomes with an average diameter of 10.2 μm and a high aspect ratio of 17.5. A mechanical model is built to illustrate that the trichomes reentrant curvature should be a key factor to inducing the superhydrophobic state of the kapok petal. To support the proposed mechanism, gold-wire trichomes with a reentrant curvature are fabricated and the results show that a superhydrophobic state can be induced by the microstructures with a reentrant curvature surface. Taking the scalability and cost-efficiency of microstructure fabrication into account, we believe the biomimetic structures inspired by the superhydrophobic kapok petal can find numerous applications that require a superhydrophobic state.

中文翻译：

---

木棉花瓣：由微型毛状体诱导的超疏水表面

首次报道木棉花瓣表现出静态水接触角高于150°的超疏水特性。有趣的是，与大多数具有层次形态的天然超疏水表面（如荷叶和玫瑰花瓣）相比，木棉花瓣上存在单尺度微毛状体并且不再有纳米晶体。实验结果表明，木棉花瓣无论是在空气中还是在油中都具有极好的自洁能力。进一步的扫描电子显微镜表征表明，超疏水状态是由平均直径为 10.2 的密集分布的微型毛状体引起的 μm 和 17.5 的高纵横比。建立了一个力学模型来说明毛状体的可重入曲率应该是诱导木棉花瓣超疏水状态的关键因素。为了支持所提出的机制，制造了具有凹曲率的金线毛状体，结果表明具有凹曲率表面的微结构可以诱导超疏水状态。考虑到微结构制造的可扩展性和成本效益，我们相信受超疏水木棉花瓣启发的仿生结构可以找到许多需要超疏水状态的应用。