Laser-induced periodic surface structures (LIPSS) is the sub-wavelength periodic nanostructure, which is generally generated by the femtosecond laser. There are two kinds of LIPSS, low spatial frequency LIPSS (LSFL) and high spatial LIPSS (HSFL), and the period size is close and less than half of the laser wavelength, respectively. Fabrication of two-dimensional (2D) LSFL and HSFL on a titanium surface with a linear-polarized femtosecond green laser beam (wavelength 515 nm) and cross-scanning strategies is demonstrated in this study. Four types of LIPSS structures are obtained by controlling the laser fluence, irradiated pulses, and cross-scanning strategies: 1D-LSFL perpendicular to laser polarization with a period of 300–360 nm, 1D-HSFL parallel to laser polarization with a period of 55–75 nm, 2D-LSFL dot-like structures with a period ~200 nm, and 2D-HSFL net-like structures with a period of 50–100 nm.
This study describes a method for fabricating a superhydrophobic surface on glass via a colloidal deposition technique based on solvent evaporation-induced aggregation. Silica nanoparticles with a low grafting density of long-chain poly-(cyclohexyl methacrylate) (PCH) were dispersed in a binary solvent system consisting of tetrahydrofuran (THF) and methanol (MeOH) with an azeotropic point and the nonfluorinated and hydrophobic PCHMA having a solubility parameter similar to that of THF. In the early stages of evaporation, the binary mixtures tend to induce the aggregation of PCH-NP due to the azeotropic point of the solvent components, leading to the formation of surface structures ranging from smooth to rough on the substrate. By adjusting the initial ratio of the binary solvents, a superhydrophobic coating with a water contact angle of 154 ± 2°and a sliding angle of less than 10°was achieved at a THF content of 60 wt %. This facile approach using azeotropes successfully shows that changes in the solvent composition of the binary solvent system during evaporation can be used to prepare superhydrophobic coatings with well-controlled surface structures.
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