Superhydrophobic Polylactic Acid Surfaces by Pregrinding and TiO2 Nanoparticle Coating

Superhydrophobicity of different materials has become a hot research topic. However, it is still challenging to realize a hydrophobic-to-superhydrophobic transition quickly by a simple process. This is mainly limited by how the surface roughness and stability of the material are constructed. Herein, we successfully prepare a superhydrophobic surface of the polylactic acid (PLA) sheet which is fabricated by an innovative and convenient method of pregrinding and postcoating. The result indicates that PLA coating materials with a multiscale hierarchical micronanostructure exhibit excellent superhydrophobic and self-cleaning properties. PLA coating in a TiO2 nanoparticle suspension without pregrinding resulted in the formation of a four-level hierarchical structure with a water contact angle (WCA) between 120 and 130°. PLA coating sheets with pregrinding in the same suspension possess the resulting multiscale hierarchical structure with a WCA more than 150°, showing superhydrophobicity. This study provides a basis for the design of self-cleaning materials and promotes the wider application of PLA-based superhydrophobic materials.