Fluorinated monomers addition

Research on fluorine-containing condensation polymers is rather limited compared to that on fluorine-containing addition polymers. This fact is attributed to the difficulty in synthesis and the high cost of fluorine-containing condensation monomers. Recently, 2,2-bis(4-hydroxyhpenyl)-1,1,1,3,3,3-hexafluoropropane (Bisphenol AF) with a hexafluoroisopropylidene unit, HOC6H4C(CF3)2-C6H4OH, was produced commercially from hexafluoroacetone and phenol, and now Bisphenol AF and its derivatives are available as condensation monomers. 

In addition, the chlorofluorinated Cl(CFClCF2)n chain activates the CC13 end group. Thus, the telomers produced can be used as original telogens for various telomerisations of non fluorinated monomers leading e.g. to form diblock cotelomer 6 [220,221 ] ... 

Compartmentalization by sequential monomer addition was also successfully demonstrated in the chemoenzymatic synthesis of block copolymers in SCCO2 using lH,lH,2H,2H-perfluorooctyl methacrylate (FOMA) as an ATRP monomer. Detailed analysis of the obtained polymer P(FOMA-i>-PCL) confirmed the presence of predominantly block copolymer structures (16). The clear advantage of the SCCO2 in this approach is that unlike conventional solvents it solubilises the fluorinated monomer. 

In addition, PAs from adamantane substituted tri-phenylamine (TPA) moiety have been prepared to study the effect of the fluorinated monomer on the final properties of PAs (Figure 4.27) [63]. All these TPA-containing polymers showed high gas permeabihty and permselectivity. But among these, the PA (PA-xl) derived from 4,4 -(hexafluoroisopropy lidene)te(benzoic acid) exhibited the highest gas... 

FKM elastomers are fluorine-containing hydrocarbon polymers with a saturated structure obtained by polymerizing fluorinated monomers such as vinylidene fluoride, hexafluoropropene, and tetrafluoroethylene. In addition to being able to operate at elevated temperatures they are also generally serviceable in dynamic applications down to — 10°F (—23°C). Thickness of material determines the flexibility at low temperatures, i.e., the thinner the material the more flexible. The brittle point at a thickness of 0.075 in. (1.9 mm) is in the neighborhood of —50°F (—45°C). Depending on the thickness and hardness of the material this temperature can have a range of —25 to -75°F (-32 to -59°C). 

Grafting of fluorinated styrene monomers such as a, yff-trifluorostyrene before proceeding to sulfonation [138]. However, such fluorinated monomers require careful handing and special set-up as well as safety procedures, which eventually introduce a tremendous additional cost to the economy of these membranes. 

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