Interference lithography with functional block copolymer blends: Hierarchical structuration and anisotropic wetting

Abstract

This manuscript describes the preparation of hierarchically, i.e. micro and nanometer scale ordered surfaces with variable functionality by simultaneously combining the microfabrication using Laser Interference Lithography (LIL) and the self-assembly of block copolymers occurring at the nanometer scale. The block copolymers employed in this study are a double hydrophobic poly(2,3,4,5,6-pentafuorostyrene)-block-polystyrene (P5FS-b-PS) and an amphiphilic polystyrene-block-poly(acrylic acid) (PS-b-PAA) diblock copolymer. The incorporation of these block copolymers in the photosensitive mixture resulted in surfaces with hierarchically micro and nanostructured interfaces with either hydrophobic or hydrophilic surface chemical composition. Moreover, in comparison with microstructured surfaces prepared using statistical copolymer with similar composition, the use of block copolymers enhanced both the surface wettability changes and the final anisotropic wetting. We evidenced herein that by preparing unidirectional micrometer size patterns with either P5FS-b-PS or PS-b-PAA the wetting anisotropy increases with the hydrophobicity or the hydrophilicity of the surface.