The Lowest Surface Free Energy Based on −CF₃ Alignment

Abstract

Free energy was measured for the surface of regular aligned closest hexagonal packed −CF3 groups. n-Perfluoroeicosane was vapor deposited onto glass, which gave epitaxially grown single-like crystallites with their molecular axes perpendicular to the glass surface. The dynamic contact angle of water on its surface was 119°, which corresponds to a surface free energy of 6.7 mJ/m2. This value is considered to be the lowest surface free energy of any solid, based on the hexagonal closed alignment of −CF3 groups on the surface.