Patent ID: 8557883

Claim:
An expanded copolymeric material comprising: a functional tetrafluoroethylene (TFE), copolymer comprising: (a) a first portion comprising a polymer chain of TFE and at least one comonomer having a functional group that is pendant to the polymer chain; and (b) a second portion consisting essentially of TFE monomers, wherein said functional group imparts a chemical or physical property to said expanded copolymeric material upon reaction with a chemical reactant or reagent, wherein said functional group is at least one member selected from the group consisting of: —COON and salts thereof, —COOR where R is alkyl, —OCOR where R is alkyl, —C≡N, —SO 2 X, where X is F or Cl, —SO 3 H and salts thereof, —SO 2 —NHN—SO 2 —, —O—P(═O)OH 2 and —N═C═O.