Physicochemical Nature of Perfluoroalkyl Compounds Induced by Fluorine

Abstract

Perfluoroalkyl (Rf) compounds have unique characters represented by a significantly high hydrophobic property, which often makes us consider that Rf groups should be interacted with each other via the ‘hydrophobic interaction’ as found for a normal hydrocarbon. Due to a similar intuitive and simplistic speculation, the Rf-specific material properties have long been enveloped in darkness for comprehensive understanding, which should lucidly be discussed within a framework of physical chemistry. Here, we show studies on the stratified dipole arrays (SDA) theory, which readily explains the Rf-specific material characters in a comprehensive manner based on only a few fundamental physical parameters of fluorine. The SDA theory encompasses some conventional theories that account for only a part of material properties. In addition, we show that the concept of vibrational spectroscopy of Rf compounds should also be revised, since the mass of fluorine is larger than that of carbon, which is opposite to the hydrocarbon case. In this manner, chemistry of Rf compounds needs another fully revised concept, which cannot be replaced by an extended concept of normal hydrocarbon compounds.