Superhydrophobicity Graving on Metallic Surface via Hierarchical Structure

Abstract

Using a sub-five picosecond laser, we investigated the creation of diverse surface structures on carbon nanotube-reinforced polymer composites. The composite material exhibited a transition in surface properties, beginning with laser-induced periodic surface structures (LIPSS) at a scale of approximately 1 μm, transforming into a double structure consisting of grains and LIPSS with mountain-like features. By conducting contact angle measurements, we assessed the wettability of the composite surface and observed a remarkable shift from hydrophilicity (63.6°) to superhydrophobicity (160.0°) as a result of the laser processing. This change led to an increase in the contact angle by approximately 100.0°, which was attributed to the creation of hierarchical surface structures showcasing the rose petal effect. Additionally, we quantified the contact angle hysteresis and surface roughness for further characterization. The utilization of a picosecond laser in generating such surfaces represents a promising and cost-effective alternative to femtosecond laser techniques.