Rose petal wetting behavior realized by ultrathin laser-induced graphene

Abstract

Laser-induced graphene (LIG) has emerged as a promising carbon nanomaterial platform owing to its scalability and tunable surface properties. Although its electrical and structural characteristics have been widely explored, the precise modulation of the surface energy remains challenging, particularly in ultrathin configurations. In this study, we investigated the wetting behavior of an ultrathin LIG synthesized from a fluorinated polyimide (F-PI) thin-film precursor using ultraviolet (UV) laser irradiation. Systematic variations in laser exposure induced morphologic transitions from hierarchical porous networks to compact planar structures, accompanied by changes in the chemical composition, including fluorine depletion and oxygen incorporation. These combined effects result in a broad range of wetting behaviors, including superhydrophobicity and hydrophilicity. Remarkably, LIG produced under single irradiation exhibited a rose-petal-like wetting state characterized by a high contact angle and strong droplet adhesion, a phenomenon not previously reported in LIG systems. This work elucidates the interplay between laser-induced nanostructuring and surface chemistry in governing wetting behavior and establishes a controllable strategy for fabricating functional carbon surfaces for applications in microfluidics, selective adhesion, and water-repellent coating technologies.