2,2,4-trifluoro-5-trifluoromethoxy 3-dioxole

The other commercial dioxole monomer is 4-trifluoromethoxy-2,2,5-trifluoro-l, 3-dioxole, (TDD, XXI). Copolymers of TDD and tetrafluoroethylene are produced and sold by Solvay-Solexis as Hyflon AD amorphous fluoropolymer (XXII).Monomer XXII (TDD) has been synthesized by two related routes via perfluorohypofluorite intermediates (Eq 13.20). In the first route, trifluoromethylhypofluorite formed from either COF2 or CO and fluorine is added... 

PRA Prabhakar, R.S., Freemarr, B.D., and Rorrrarr, I., Gas arrd vapor sorption and permeation in poly(2,2,4-trifluoro-5-trifluoromethoxy-l,3-dioxole-co-tetrafluoro-ethylene). Macromolecules, 37,7688, 2004. 

Asymmetric and composite membranes commercially known as HYFLON AD are obtained from copolymers of tetrafluoroethylene (TFE) and 2,2,4-trifluoro-5-trifluoromethoxy-l,3-dioxole (TTD) these membranes show a high hydrophobic character with contact angles to water greater than 120° (Arcella et al. 1999). Hydrophobic membranes from copolymers of polytetrafluoroethylene (PTFE) and polyvinylidenefluoride (PVDF) were prepared by a phase inversion process (Feng et al. 2004) these membranes exhibit excellent mechanical properties and good hydrophobicity (contact angle to water of about 87°). 

Poly[tetrafluoroethylene-co-perfluoro(vinyl methyl ether)] Poly(tetrafluoroethylene-co-2,2,4-trifluoro-5-trifluoromethoxy-1,3 -dioxole)... 

Hyflon AD is an amorphous perfluorinated copolymer of tetrafluoroethylene (TFE) and 2,2,4-trifluoro-5-trifluoromethoxy-l,3-dioxole (TTD). Compared to the situation in the Teflon AF series, the reduced intermolecular distance due to the structural change result in moderate fractional free volume of 23%. Thus, the gas permeabilities are lower than those of Teflon AF membranes, allowing the increase of permselectivities. While this fluoropolymer has the advantage of solubility in fluorinated liquid, such as Galden FIT 55 and HFE 7100, the permeation properties are affected by the kind of residual solvents as well. 

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