利用分形结构修饰疏水表面的研究

Researching on Decoration of the Hydrophobic Surface by Utilizing Constructing Fractal Structure

针对某种材料表面设计合理的粗糙结构是增大接触角进而提升材料疏水性的主要方法。通过理论分析无分形结构下水滴在硅树脂表面不同粗糙度下存在的Wenzel模型和Cassie模型2种接触状态关系以及接触角大小,得出同等接触角下Cassie状态粗糙表面更易修饰;对比分形结构对2种接触模型的作用效果,分形结构修饰后2种模型接触角均增大,且一定分形级数内Cassie接触状态接触角增幅明显。利用分子动力学模型仿真分析无分形结构以及存在二级分形结构时对Cassie状态接触角影响,取4种不同粗糙结构进行对比,仿真结果显示固体表面存在二级分形结构时,接触角增大约5°,将仿真结果与理论值相比较,误差约1%,对Cassie状态粗糙度修饰分形结构可提升疏水性。

For a material, the design of a reasonable surface roughness structure is a main method to increase the contact angle between it and the liquid, increasing the hydrophobic of the material. In this paper, the two contact state relationships and contact angle on the solid surface, including Wenzel and Cassie states, are analyzed theoretically, and the effect of the fractal structure on the two contact models is compared. A good hydrophobic effect can be obtained by modifying the rough structure of Cassie contact state. The influence of no-fractal structure and the existence of two-level-fractal structure on the contact angle of Cassie state are analyzed by using molecular dynamics model. The contact angles of the two contact states increase with the modification of fractal structure, especially the increase of Cassie state. The simulation results show that when the two dimensional fractal structure exists on the solid surface, the contact angle increases by 5°compared with the surface without fractal structure. The error between simulation value and theoretical value is about 1%. A good hydrophobic effect can be obtained by modifying the rough structure of Cassie contact state by using fractal structure in certain fractal series.