Surface characteristics of water-repellent polyelectrolyte multilayer films containing various silica contents

摘要

Water-repellent films were dip-coated onto glass substrate by mimicking a unique surface feature of the lotus leaf by a layer-by-layer deposition of polyelectrolyte, followed by SiO_2 particle to modify surface roughness, and finally a semifluorinated silane to lower the surface energy. Two types of the SiO_2, a fine-sized Aerosil~® 200 and a coarse-sized Aeroperl~® 300/30, were employed at various contents to modify the films' surface roughness. SEM and AFM analysis revealed that the Aerosil~® 200 had more uniform deposition onto the etched polyelectrolyte layer due to its very fined size while the Aeroperl~® 300/30 had less uniform deposition due to its coarser size. In both cases, higher SiO_2 content in the films led to more surface roughness and more hydrophobicity, although the effect was not dramatic in the case of Aerosil~® 200. The films containing the Aerosil~® 200 had very high contact angles of 167-175°and very low surface energy of 0.03-0.51 mJ m~(-2), while the films containing the Aeroperl~® 300/30 had lower contact angles of 132-154°and higher surface energy of 3.07-11.29 mJ m~(-2).