Process for manufacturing clean fluoropolymers

A fluoroelastomer derived from an emulsion polymerization comprising a fluorinated emulsifier represented by the formula:

• F—(CF2)t-[O(CF2)n]m-O—(CHF)o-(CF2)p-X
• wherein m=0 to 3;
• n=1 to 3;
• o=0 to 1;
• p=1 to 3;
• t=1 to 10;
• and wherein when t=2 than o≠0;
• and further wherein X is selected from a group consisting of a carboxyl acid group and a salt of a carboxylic acid group,
• and wherein the fluoroelastomer is essentially free of cations other than NH4+ and H+.

A fluoroelastomer obtained by a process comprising:

• (a) polymerizing a fluoromonomer and a cure site monomer in an aqueous emulsion polymerization process to form an aqueous composition comprising a fluoroelastomer;
• (b) coagulating the aqueous composition with a metal salt to form a coagulated fluoropolymer;
• (c) drying the coagulated fluoropolymer;
• wherein the polymerization process is carried out with the aid of a fluorinated emulsifier represented by the formula:
• F—(CF2)t-[O(CF2)n]m-O—(CHF)o-(CF2)p-X
• wherein m=0 to 3;
• n=1 to 3;
• o=0 to 1;
• p=1 to 3;
• t=1 to 10;
• and wherein when t=2 than o≠0;
• and further wherein X is selected from a group consisting of a carboxyl acid group and a salt of a carboxylic acid group,
• wherein the fluoroelastomer is essentially free of cations other than NH4+ and H+.

An article prepared from a fluoroelastomer derived from an emulsion comprising a fluorinated emulsifier represented by the formula:

• F—(CF2)t-[O(CY1Y2)]m-O—(CY3Y4)-X
• wherein CY1Y2 represents a perfluorinated or partially fluorinated linear alkylene having from 1 to 4 carbon atoms, CY3Y4 represents a perfluorinated, partially fluorinated or non-fluorinated, linear alkylene having from 1 to 4 carbon atoms, t is from 1 to 10, m is 0 to 3;
• X is selected from a group consisting of a carboxyl acid group and a salt of a carboxylic acid group,
• and wherein the fluoroelastomer is essentially free of cations other than NH4+ and H+.