Preparation And Properties Of Fluorine-free Superhydrophobic Copper Surfaces

In this research, superhydrophobic surfaces based on copper substrate were prepared without the modification of low surface energy material. Rough microstructures formed on the surface of copper and the surface exhibited superhydrophobicity after the modification of precious metals, base metals and non-metallic respectively. The samples were systematically characterized using contact Angle（CA） Measurement, field emission scanning electron microscopy（FE-SEM）, X-ray Spectrometer（EDS）, X-ray Diffraction（XRD） and X-ray Photoelectron Spectroscopy（XPS）. Additionally, the stabilities of the superhydrophobic samples under the UV light irradiation and ambient condition were carefully investigated. The main contents are as following:1、Superhydrophobic surface was prepared through chemical deposition without using low surface energy modified material. The surface has an excellent super hydrophobicity with a contact angle greater than 160 °and sliding angle less than 5°. A layer of cauliflower-like nano-structure surface can be observed by FE-SEM on the copper after the immersion of copper into the solution of gold chloride acid and chloroplatinic acid, respectively. Gold and platinum were deposited on copper surface respectively through substitution reactions. The noble metal modified sample surface exhibited reversible transition from superhydrophobicity to superhydrophilicity by UV irradiation. The sample became superhydrophilic after UV irradiation and recovered its superhydrophobicity via heat treatment. In addition, the sample still possessed excellent superhyrophobicity even after repeatedly irradiation/heating cycles.2、Superhydrophobic surface was prepared through electro-deposition without using low surface energy modified material. The surface has an excellent super hydrophobicity with a contact angle of 162.0° and a sliding angle of 4.1°. The optimum conditions of electro-deposition were detected and that were the voltage of 2.5 V, the reaction time of 180 s and temperature of 40 °C. A layer of cyatheaceae leaves-like nanostructures were observed by FE-SEM on copper surface. The principle was that the anode graphite reduced Cu²⁺ to Cu species, which were deposited on copper surface. The copper modified sample surface exhibited reversible transition from superhydrophobicity to superhydrophilicity by UV irradiation. In addition, the sample still possessed excellent superhyrophobicity even after repeatedly irradiation/heating cycles.3、Superhydrophobic surface was prepared through chemical deposition without using low surface energy modified material. The surface has an excellent super hydrophobicity with a contact angle of 152.8° and a sliding angle of 8.1°. The results showed that the optimum reaction time was 30 min according to the research. After a series of abservation and characterization by FE-SEM and XPS, the surface was composed of CuCl cube crystal micro/nano-structures, which increased the surface roughness. The principle of this research was that Cu²⁺ of CuCl₂ solution was reduced to Cu¹⁺ of CuCl particles by disproportionation reaction, the so-obtained CuCl was deposited on copper surface. The copper modified sample surface possessed excellent superhydrophilicity and recovered its superhydrophobicity after stored in darkroom for a period of time. However, the copper modified sample surface has no reversible transition from superhydrophobicity to superhydrophilicity by UV irradiation.