蝴蝶翅表面多级微/纳结构疏水模型及耦合机理

Multiple-dimensional micro/nano structural models for hydrophobicity of butterfly wing surfaces and coupling mechanism

使用扫描电子显微镜（SEM）、接触角测量仪和红外光谱仪（FT-IR），观测了27种蝴蝶翅表面的微观结构、复合浸润性和化学成分．利用Cassie方程建立了蝴蝶翅表面微／纳结构疏水模型，从生物耦合角度探讨了疏水机理．结果表明，蝴蝶翅表面由天然疏水材料组成，具有复杂的多级微／纳结构，包括一级结构（微米级鳞片）、二级结构（纳米级纵肋和横桥）和三级结构（纳米级突起）．翅表面具有高疏水性（接触角138°～157°）和低黏附性（滚动角1°-3°）．翅表面微观形貌和自清洁性具有显著的各向异性．这种特殊的复合浸润性是材料耦元与结构耦元耦合怍用的结果．微米级鳞片的宽度越小、间距越大，纳米级纵助的高度越小、宽度越小、问距越大，翅表面疏水性越强．研究结果有助于进一步流调结果揭示生物表面的疏水机理，为智能界面材料的仿生设计和制备提供启示．

The microstructure, wettability and chemical composition of the butterfly wing surfaces were investigated by a scanning electron microscope, a contact angle meter and a Fourier transform infrared spectrometer. The micro/nano structural models for hydrophobicity of the butterfly wing surfaces were established on the basis of the Cassie equation. The hydrophobicity mechanisms were discussed from the perspective of biological coupling. The butterfly wing surfaces are composed of naturally hydrophobic material and possess micro/nano hierarchical structures, including primary structure （micrometric scales）, secondary structure （nano longitudinal ridges and lateral bridges） and tertiary structure （nano stripes）. The wing surfaces exhibit high hydrophobicity （contact angle 138°-157°） and low adhesion （sliding angle 1°-3°）. The micromorphology and self-cleaning performance of the wing surfaces demonstrate remarkable anisotropism. The special complex wettability ascribes to a coupling effect of the material element and the structure element. In microdimension, the smaller the width and the bigger the spacing of the scale, the stronger the hydrophobicity of the wing surfaces. In nano-dimension, the smaller the height and the smaller the width and the bigger the spacing of the longitudinal ridge, the stronger the hydrophobicity of the wing surfaces. This work promotes our understanding of the hydrophobicity mechanism of bio-surfaces and may bring inspiration for biomimetic design and preparation of smart interfacial materials.