Fabricating superhydrophobic and oleophobic surface with silica nanoparticles modified by silanes and environment-friendly fluorinated chemicals

Abstract

Fluorinated polymers or fluorinated chemicals are often used to enhance the hydrophobicity and oleophobicity of surfaces. In this work, amphiphobic coating surfaces of silica nanoparticles modified by methyltrimethoxysilane (MTMS), ethyltriethoxysilane (ETES) or/and 1H,1H,2H,2H-perfluorooctyltriethoxysilane (HFOTES) were fabricated via a sol-gel process. The results demonstrated that the surface wettability of coatings was greatly influenced by the type of silanes which were used to modify silica, and superhydrophobic and oil-repellent coating surface was obtained by using silica co-modified by MTMS and HFOTES (MF-SiO2). The water contact angles of dip-coated MF-SiO2 coatings could reach to 150.2° with the lowest angle of water hysteresis (3.3°) among all samples. One reason was that the addition of MTMS changed the holes structures of F-SiO2, and the co-modified surface of MF-SiO2 formed the multi-scale rough structures. Moreover, the percentage of fluorine at the surfaces for sample MF-SiO2 was greatly increased due to the packing of CF3 groups on surface. In other words, the addition of MTMS influenced the outmost layer of coating and changed the distribution of fluorinated chemical groups for sample MF-SiO2. Therefore, the coating for sample MF-SiO2 could exhibit superhydrophobic and oil-repellent properties owing to the multi-scale surface roughness as well as the packing of CF3 groups on the outmost layer of surface.