Thermal stability of micro–nano structures and superhydrophobicity of polytetrafluoroethylene films formed by hot embossing via a picosecond laser ablated template

• Published in: Applied surface science 2015-03, Vol.331, p.437-443
• Main Authors: Gong, Dingwei, Long, Jiangyou, Fan, Peixun, Jiang, Dafa, Zhang, Hongjun, Zhong, Minlin
• Format: Article
• Language: English
• Subjects: Ablation; Collapse; Dual-scale structure; Embossing; Flats; Hot-embossing; Lasers; Nanostructure; Polytetrafluoroethylenes; Superhydrophobicity; Thermal stability
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2015.01.102

•The dual-scale structural PTFE films in superhydrophobicity have been realized efficiently.•The parameters influence in hot-embossing process has been analyzed in detail.•The thermal stability of structural PTFE films has been systematically discussed.•The dual-scale structural of PTFE films surface presented their thermal stability until 340°C. We report here a simple and efficient hot embossing process capable of mass fabricating superhydrophobic and self-cleaning polytetrafluoroethylene (PTFE) film surfaces. Adding superhydrophobicity to hydrophobic polytetrafluoroethylene (PTFE) significantly enhances their application potential in industry as well as in daily life. We applied a picosecond laser to fabricate regular array of micro-holes companied with submicron structures on high strength steel substrate to form a lotus-leaf-like template. Then the hot embossing process was performed on flat PTFE films to introduce a dual-scale structure composed of the micro-scale protrusions and nano-scale fibril structures on the top of protrusions. The hot embossing parameters such as the embossing pressure and time were optimized to achieve required micro- and nano-scale dual structure on PTFE film very closed to the similar dual structure of the lotus leaf surface. The PTFE films then exhibited superhydrophobicity with contact angle up to 154.6° and sliding angle of as low as 5.5°. The thermal stability of the superhydrophobic PTFE films was investigated from room temperature up to 430°C. We demonstrate that the micro–nano dual structure on PTFE films and their superhydrophobicity is thermally stable up to 340°C. The micro-scale protrusions will collapse and the superhydrophobicity will lose when the temperate is over 370°C.