Effect of Structure Hierarchy for Superhydrophobic Polymer Surfaces Studied by Droplet Evaporation

Nanomaterials

卷:8

Rafael Taboryski¹  Peter Johansen²  Lars Christensen²  Nastasia Okulova² 

[1] DTU Nanotech, Technical University of Denmark, DK-2800 Lyngby, Denmark;

[2] Danapak Flexibles A/S, DK-4200 Slagelse, Denmark;

关键词: hierarchical structures;    super-hydrophobic surfaces;    droplet evaporation;    Cassie-Baxter;    contact angle hysteresis;   

DOI  :  10.3390/nano8100831

来源: DOAJ

【 摘 要 】

Super-hydrophobic natural surfaces usually have multiple levels of structure hierarchy. Here, we report on the effect of surface structure hierarchy for droplet evaporation. The two-level hierarchical structures studied comprise micro-pillars superimposed with nanograss. The surface design is fully scalable as structures used in this study are replicated in polypropylene by a fast roll-to-roll extrusion coating method, which allows effective thermoforming of the surface structures on flexible substrates. As one of the main results, we show that the hierarchical structures can withstand pinning of sessile droplets and remain super-hydrophobic for a longer time than their non-hierarchical counterparts. The effect is documented by recording the water contact angles of sessile droplets during their evaporation from the surfaces. The surface morphology is mapped by atomic force microscopy (AFM) and used together with the theory of Miwa et al. to estimate the degree of water impregnation into the surface structures. Finally, the different behavior during the droplet evaporation is discussed in the light of the obtained water impregnation levels.

【 授权许可】

Unknown