Perfluoropolycycloalkanes

Fluorochemical compositions comprising carbonyl fluoride compounds in the form of perfluoropolycycloalkane ring assemblies each having (a) at least two and less than seven perfluorinated cyclohexane rings, or (b) at least two and less than seven perfluorinated decahydronaphthalene fused ring systems, or (c) combinations of at least one of said perfluorinated cyclohexane rings with at least one of said perfluorinated decahydronaphthalene fused ring systems, the sum of the perfluorinated cyclohexane rings and perfluorinated decahydronaphthalene fused ring systems being less than seven, each perfluorinated ring or ring system being directly joined to another perfluorinated ring or fused ring system by a single bond and the ring assembly having a total of at least 13 carbon atoms, said compounds having --COF ring substituents.