Superhydrophobic polyethylene films by catalytic ethylene polymerization

Polyethylene films were grown on a flat silica surface modified by the bis(imino)pyridyl iron(II) catalyst during ethylene polymerization in an organic solvent. The resulting films show under certain polymerization conditions superhydrophobic properties. The development of the nascent polymer morphology which leads to the superhydrophobic behavior depends strongly on the polymerization conditions, especially the solvent and the polymerization temperature. Advancing water contact angle as high as 169° and sliding angles as low as 2° for a 10 μl droplet are obtained on these films. SEM images reveal special surface structures of these films containing micrometer-sized islands, submicrometer particles on the islands, and stress nanofibers between the islands, which - in combination - render superhydrophobicity to the polyethylene surfaces.