Study of the Femtosecond Laser Processed Surfaces, Imprinting, and Casting for Changing the Wettability of Surfaces

Femtosecond Laser Surface Processing (FLSP) is a technology to fabricate micro/nano surface structures. These patterned surface structures show great importance in many applications, especially in controlling the wettability of the surface. Imprinting is a typical method for manufacturing large volumes of surfaces. This study combines two processes (FLSP and stamping) together to produce a surface structure similar to the original FLSP surface. In the first step, micro/nano structured surface mounds were fabricated by femtosecond laser processing. Then, these FLSP surfaces served as molds for subsequent imprinting to replicated the “negative” surface on a blank material. Surface morphology and peak-to-valley roughness of the imprinted surface was used to quantify the imprint quality, while droplets tests were conducted to measure the wetting property of the surface. The imprinting experiments had two parallel branches, one was stamping, the other was casting. Stamping experiments were conducted on different materials. These materials were divided into metals and polymers. A finite element model for single mound stamping was investigated to study the influence of material and geometry. The model was verified by experiments. A variety of experiments were conducted to investigate the effect of temperature and pressure on the imprint quality. Different FLSP surface stamps were also produced to investigate the morphology’s influence on the imprinted surface as well. Casting experiments were conducted twice to produce “negative” and “positive” surfaces related with the FLSP surface. These imprinted surfaces had changed their wetting property due to the patterned surface structure. An anti-icing test was conducted on these imprinted sample surfaces. The results from this test showed that the anti-icing property of material was related to its wetting behavior. The superhydrophobic surface had the best performance for anti-icing. Adviser: Jeffrey Shiel