Acta Chimica Sinica ›› 2014, Vol. 72 ›› Issue (10): 1075-1078.

Communication

### 疏水表面拓扑结构对其润湿状态影响的粗粒化模拟

1. 华南理工大学化学与化工学院 广东省绿色化学产品技术重点实验室 广州 510640
• 投稿日期:2014-07-04 修回日期:2014-10-08 发布日期:2014-10-08
• 通讯作者: 周健 E-mail:jianzhou@scut.edu.cn
• 基金资助:

项目受国家自然科学基金(Nos. 21376089， 91334202)资助.

### Effect of Topology of Hydrophobic Surfaces on Their Wetting States by Coarse-grained Simulations

Quan Xuebo, Dong Jiaqi, Zhou Jian

1. School of Chemistry and Chemical Engineering, Guangdong Provincial Key Lab for Green Chemical Product Technology, South China University of Technology, Cuangzhou 510640
• Received:2014-07-04 Revised:2014-10-08 Published:2014-10-08
• Supported by:

Project supported by the National Natural Science Foundation of China (Nos. 21376089, 91334202).

Researches have showed that there are two factors that can affect the wettability of solid surface: the chemical composition and the surface roughness. In this communication, coarse-grained molecular dynamics simulations based on BMW-Martini force field were used to study the effect of surface topology of hydrophobic surfaces on their wetting states. Simulation results show that the increase of surface roughness has little effect on the hydrophobicity of a hydrophobic surface, but does have effect on its wetting state. For the studied pillar spacing ranges (d≤4.7 nm), the wetting behavior of water droplets on hydrophobic surfaces with pillared structure is affected by two factors, i.e., pillar spacing and pillar height. For each pillar spacing, there exists a critical pillar height; a wetting transition from the Wenzel state to the Cassie-Baxter state on pillared hydrophobic surface can be observed, and the critical pillar height increases with the pillar spacing. Through a further analysis for the studied surfaces, we find that the wetting transition is related to the ratio of pillar spacing to pillar height, when the ratio is no more than 2, the Wenzel wetting state can be observed; while when the ratio exceeds 2, the Cassie-Baxter state can be observed. Through energy analysis, we find that the wetting transition is mainly dependent on the Van der Waals interaction. When the roughness of a surface is below the critical value, the interaction between the water droplet and surface is very strong, so that water droplet can easily enter into the space between pillars on the surface to form Wenzel state; however, when exceeding the critical value, the interaction between water droplets and surface is weakened, and water droplet is difficult to enter into the gaps, so a Cassie-Baxter state can be observed. This work could provide some guidance for the development of hydrophobic materials.