| abstract |
A process comprising polymerizing at least one fluorinated monomer in an aqueous medium containing initiator and polymerization agent to form an aqueous dispersion of particles of fluoropolymer, the polymerization agent comprising: fluoropolyether acid or salt thereof having a number average molecular weight of at least about 800 g/mol; and fluorosurfactant having the formula: n n[R 1 —O n -L-A − ]Y + nwherein: n R 1 is a linear or branched partially or fully fluorinated aliphatic group which may contain ether linkages; n is 0 or 1; L is a linear or branched alkylene group which may be nonfluorinated, partially fluorinated or fully fluorinated and which may contain ether linkages; A − is an anionic group selected from the group consisting of carboxylate, sulfonate, sulfonamide anion, and phosphonate; and Y + is hydrogen, ammonium or alkali metal cation; with the proviso that the chain length of R 1 —O n -L- is not greater than 6 atoms. |