ABSTRACT
Perfluoroalkylpolyether (PFPE) fluids were first synthesized by DuPont in 1959 and disclosed in 1965. PFPE oils are colorless and odorless fluids. Physical properties that vary with molecular weight are density, pour point, viscosity, viscosity index, volatility, and vapor pressure. Metal fluorides can catalyze the decomposition of PFPE oils, especially those PFPE oils that contain the difluoroformyl group. The hydrolytic stability of PFPE oils is exceptional. Long-term contact with steam or boiling water produces no adverse effects on the PFPE fluids. PFPE oils are not soluble in common solvents, acids, and bases, but some solvents will dissolve in PFPE oils. The densities of PFPE fluids are nearly twice that of hydrocarbon lubricants. PFPE oil viscosity increases with an increase in the molecular weight. Commercial PFPE polymers are fractionated by distillation to produce a series of grades, based on viscosity. PFPE oils are considerably more compressible, with lower bulk modulus, than conventional petroleum hydraulic fluids.
