Solvent-free Fabrication of Flexible and Robust Superhydrophobic Composite Films with Hierarchical Micro/nanostructures and Durable Self-cleaning Functionality.

Abstract

Superhydrophobic surfaces hold tremendous potential in a wide range of applications owing to their multifaced functionalities. However, the mechanochemical susceptibility of such materials hinders their widespread usage in practical applications. Here, we present a simple, solvent-free and environmentally friendly approach to fabricate flexible and robust superhydrophobic composite films with durable self-cleaning functionality. The obtained composite film features unexpected but surprising hierarchical micro/nanoscopic structures as well as robust superhydrophobicity with water contact angle around 170° and sliding angle below 4°. Notably, the composite film exhibits mechanical robustness under cyclic abrasion, tape-peeling, flexing as well as intensive finger wiping and knife-cutting, maintains excellent superhydrophobicity after long time exposure to high humidity environment, as well as sustains exposure to highly corrosive species, such as strong acid/base solutions and organic solvents. The robust superhydrophobicity is ascribed to the induced micro/nano hierarchical surface structures, resulting in the trapped dual-scale air pockets which could largely reduce the solid/liquid interface. In addition, even after oil contamination, the composite film maintains its water repellency and self-cleaning functionality. The robust superhydrophobic composite film developed here is expected to extend the application scope of superhydrophobic materials and should find potential usage in various industries and daily life.