Preparation of hydrophilic-hydrophobic conversion on 316L stainless steel

The traditional hydrophilic-hydrophobic conversion methods have the disadvantages of the introduction elements, long time, and complex operation. In this paper, the hydrophilic-hydrophobic conversion was achieved on the surface of 316L stainless steel using electron beam irradiation (EBI) combined with low-temperature oxidation. The results demonstrated that EBI improved the contact angle from 89° to 135°. The contents of C-C/C-H hydrophobic functional groups were found to be notably increased by low electron doses in the experiments. The contents of C-O-C, O-C = O, and -OH hydrophilic functional groups decreased. The interaction of excited secondary electrons with precursor molecules generated free radical fragments that adsorbed onto surfaces and formed new chemical bonds, changing the content of the functional groups. After low-temperature oxidation, the contact angle decreased to 76°. Following a second EBI, the contact angle increased to 144°. Due to the reversible changes in the C-C/C-H, C-O-C, and O-C = O group contents, the hydrophilic-hydrophobic conversion was achieved without introducing new elements during the whole process.