Described herein is a composition comprising: a polymer derived from (a) a fluorinated olefin monomer; (b) a highly fluorinated sulfur-containing monomer of the formula: €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ CX 1 X 2 =CX 3 [(CX 4 X 5 ) w -O-R 1 -SO 2 Y] where each X 1 , X 2 , X 3 , X 4 , and X 5 is independently selected from H, Cl, or F; w is 0 or 1; R 1 is a fluorinated divalent carbon-containing group, optionally comprising oxygen atoms; and Y is selected from F, Cl, Br, I, or OM, where M is a cation; and (c) a polyfunctional monomer, comprising at least two functional groups, wherein the functional groups are selected from the group consisting of: (i) a fluorovinyl ether group, (ii) a fluoroallyl ether group, (iii) a fluorinated olefinic group, and (iv) combinations thereof, wherein the composition further comprises an additive, wherein the additive comprises at least one of a manganese and cerium.