Molding Wetting by Laser-Induced Nanostructures

TL;DR

This paper demonstrates that femtosecond laser-induced nanostructures can effectively modify the wetting properties of metal surfaces, primarily through morphological changes, enabling precise control of water contact angles.

Contribution

It provides a detailed analysis of how femtosecond laser patterning alters surface morphology and chemistry to influence wetting behavior, advancing nanostructuring techniques for surface property control.

Findings

Laser-induced nanostructures increase water contact angle by ~80%.

Surface morphology changes dominate wetting property modifications.

Chemical composition changes have a lesser impact on wetting behavior.

Abstract

The influence of material characteristics - i.e., type or surface texture - to wetting properties is nowadays increased by the implementation of ultrafast lasers for nanostructuring. In this account, we exposed multilayer thin metal film samples of different materials to a femtosecond laser beam at a 1030 nm wavelength. The interaction generated high-quality laser-induced periodic surface structures (LIPSS) of spatial periods between 740 and 790 nm and with maximal average corrugation height below 100 nm. The contact angle (CA) values of the water droplets on the surface were estimated and the values between unmodified and modified samples were compared. Even though the laser interaction changed both the surface morphology and the chemical composition, the wetting properties were predominantly influenced by the small change in morphology causing the increase in the contact angle of ~80%, which could not be explained classically. The influence of both surface corrugation and chemical composition to the wetting properties has been thoroughly investigated, discussed and explained. The presented results clearly confirm that femtosecond patterning can be used to mold wetting properties.