Perfluoro polyether

A series of rather unusual new perfluoro polyethers (42) has been prepared by the reaction of fluorine with the polyether ... 

The second fluorination step is extremely temperature sensitive in the 65—70°C range, with even 2°C making substantial differences in the range of polyethers produced. A number of interesting new perfluoro polyethers were obtained as may be seen in Table VI. 

G. W. Tyndall, T. E. Karis, and M. S. Jhon, Spreading profiles of molecularly thin perfluoro-polyether films, Tribol. Trans. 42, 463 470 (1999). 

Perfluoro polyethers (Fomblin) (Krytox ) (3 x IO 8) If exposed to too much heat, decomposes to a gas rather than breaking down. Is resistant to oxidation and chemically resistant with few exceptions. No polymers are formed under energetic particle bombardment. Can be regenerated for reuse. Provides somewhat lower pumping speeds than other oils. High initial cost. Above 300 - 350°C, breaks down into aggressive and toxic compounds. To effectively remove it, chlorofluorocarbons must be used. 

For comparison, oxetanes are oligomerised in an analogous way to give intermediate polyfluoro-polyethers that are then further fluorinated to give perfluoro-polyethers in the process for the production of Demnum fluids (Daikin Co.) [188] (Figure 8.59). 

Also, intermediate peroxides are formed in the oxidation of perfluorinated alkenes, e.g. in the photo-oxidation of perfluoroethene and perfluoropropene for the formation of Fomblin (Ausimont Co.) perfluoro-polyether fluids [198, 199]. 

Beside modification of the PT catalyst by incorporation of C02-philic groups, other approaches to the problem of the poor solubility of polar compounds in SCCO2 were envisaged. Fluorinated surfactants (perfluoro-polyether ammonium carboxylates) were used as stabilizers of H2O/SCCO2 microemulsions.The nucleo-... 

Positive-ion TOF-SIMS spectrum of a perfluoro polyether. The inset shows the presence of other terminal groups. (Reprinted with permission from Ref. 23, Copyright 1990 American Chemical Society)... 

There are migrating slip additives that are not of this two part structure. One additive is perfluoro-polyether (PFPE) synthetic oil marketed by DuPont under the trademark Fluoroguard , which is an internal lubricant that imparts improved wear and... 

Other copolymers with interesting mechanical properties have been reported in the literature. Haynes et al. copolymerized PLA with perfluoro-polyether (PFPE) and observed an increase of the elongation at break up to 300% with 5% of PFPE. Another alternative was described by Pitet et al./ who synthesized ABA triblock copolymers from 1,5-cyclooctadiene (COD) and D,L-lactide. The triblocks were considerably tougher than PDLA, especially for poly-COD low midblock contents. An elongation at break of 180% was obtained for a triblock containing 0.76 volume fraction of PLA. 

Polyurethane elastomers have been made from these perfluoro-polyethers in both opaque and transparent forms and covering the following range of properties ... 

Chiavarini, M., Gaggini, F., Guidetti, V., Massa, V. (1993). Stone protection From perfluoro-polyethers to polyfluorourethanes. In M-J. Thiel (Ed.), Conservation of Stone and Other Materials Research-Industry-Media, UNESCO, Paris, June 29-July 1, 1993 proceedings (pp. 725-732). E. F.N. Spon. 

Dynamic SIMS has been used to measure polymer diffusion, e.g. interdiffusion in the PS/PPO system [205], SIMS depth profiling enables to reveal silica present at some 10 nm below the surface. DSIMS has also been used to measure the film thickness of perfluoro-polyether lubricant coated on magnetic recording media by determining the etching time to the underlying carbon overcoat layer [206],... 

Fig. 20.7. Characterization of perfluoro-polyethers by on-iine LC-ESi-MS [12]. LC conditions Coiumn Nucleosil silica (5 pm), 150 mm X 2.1 mm i.d. mobile phase 0.1-20% methyl-t-butyl ether in 1,1,2-trichlorotrifluoroethane in 15 min mass spectrometry Micromass time-of-flight MS...

---