ABSTRACT
I. INTRODUCTION Carbon atoms in hydrocarbon molecule are in a reduced state because they bind to hydrogen atom of an electronegativity of 2.1, and the C-H linkage has a moderately high bond energy of 415 kJ mol-1 while those in fluorocarbon molecule are highly oxidized, more oxidized than those binding to an oxygen atom of an electronegativity of 3.6 since they are bound to a fluorine atom with an electronegativity of 4.0, thereby making the fluorocarbon molecule very stable against oxidation. Halogen atoms are in general strongly electronegative, and the bond strength between halogen and carbon atoms is high; in particular, the F-C bond has a high bond energy of 484 kJ mol-1. Moreover, the fluorine atom is very small in size, the second smallest next to the hydrogen atom, and its van der Waals and covalent radii are merely 10% larger than those of the hydrogen atom. Nevertheless, this small difference in size makes the fluorocarbon chain a rigid, rodlike shape with a twist period of 13 carbon atoms, whereas the hydrocarbon chain takes a flexible structure. Fluorine atoms of the fluorocarbon chain densely cover the carbon skeleton inside the chain, forming a fluorine sheath.
