Recent progress of double-structural and functional materials with special wettability

It is well known that properties of materials are largely determined by their structures. Here we introduce the special double-structural materials, which are composed of micrometre and nanometre building blocks and commonly exist in nature. This review mainly focuses on recent developments of double-structural and functional materials with special wettability. We highlight excellent properties possessed by micro-and nanostructures which initially originated from the organisms with special functions in the biological world. The excellent properties shown by such structures are discussed in three parts: special wettability, mechanical properties, and optical properties, primarily including superhydrophobicity, superhydrophilicity, superoleophobicity, low and high adhesion, low friction, structural color, antireflection and so on. We will also briefly address the research prospects and directions of micro-and nano-structures. Further study on the relationship between structures and properties will be conducive to better transfer micro-and nanostructures to the engineering materials so as to obtain desired performances and a wide range of applications.