Study of surface wettability on fused silica by ultrafast laser-induced micro/nano-surface structures

Abstract

Glass materials integrated with advanced functions, such as anti-fogging and self-cleaning functions, are urgently demanded in applications such as vehicle windshields, eyeglasses, goggles, electronic device screens, and windows. Inspired by nature, researchers have found multiscale surface structures to be a crucial factor in determining a material's surface wettability. The ultrafast pulsed laser is a promising tool to induce such surface structures and subsequently control the surface functionalities on different materials. The behavior of surface wettability with different micro/nano-scale surface structures created by femtosecond laser irradiation on fused silica is investigated in this research. The effects of laser fluence, overlapping ratio, and repetition rate on the structure morphology are studied. Seven different sorts of structures can be created by manipulating these parameters: (S1) micro-dots array, (S2) micro-dots array covered with laser-induced periodic surface structures (LIPSSs), (S3) LIPSSs, (S4) microgrooves covered with LIPSSs, (S5) microgrooves covered with irregular nanostructures, (S6) micro-channels and (S7) micro-channels covered with LIPSSs. Investigations into the static contact angle show that hydrophilic and superhydrophilic surfaces can be generated through the introduction of these laser-induced hierarchical structures. The relationship between laser parameters, surface structures, surface roughness, and surface wettability is established. Different distinctive mean static contact angle values are identified for different surface structures.