Fluorinated Polyhedral Oligosilsesquioxane Surfaces and Superhydrophobicity

Abstract

Fluorinated compounds are a logical choice for hydrophobic applications owing to their generally low surface energy. Polyhedral molecules may also improve hydrophobicity by increasing material surface roughness. There have been many recent attempts to synthesize and characterize various types of fluorinated polyhedra. These reports include the fluorination or fluoroalkylation of C₆₀ [1,2]. Unfortunately, C₆₀F₄₈ (fluorinated buckminsterfullerene) cannot be used as a hydrophobic material, since it is metastable and is hydrolyzed by water [3]. However, the perfluorocarborane species, perfluoro-deca-β-methyl-para-carborane, shows remarkable hydrolytic and oxidative stability [4]. Fluorinated carbon nanotubes and nanofibers have also been produced [5]. Many of these fluorinated polyhedral compounds may be useful in hydrophobic applications, but they are generally hazardous to prepare, require air and moisture sensitive manipulations, and have limited economies of scale. For these reasons, alternative fluorinated polyhedra, such as Polyhedral Oligomeric SilSesquioxanes (POS) are highly desired (Figure 6.1).