Cross-linked polymeric ammonium salts and their use in absorbing organic contaminants

A method for absorbing at least one PFAS molecule from an aqueous medium wherein said at least one PFAS molecule comprises a water soluble fluorinated amphiphilic structure with a carbon chain length that ranges from 4 to at least 14 carbon atoms which comprises:

• contacting said PFAS molecule with at least one self-supported crosslinked polymeric ammonium salt, wherein said salt is a water-insoluble, solid polyelectrolyte having at least one polymer chain,
• wherein said polyelectrolyte comprises a copolymer network wherein ammonium nitrogen atoms are separated by group Y or group Z ordered along (i) polymer chains as N—Z—[N—Y—N—Z]n—N and along (ii) cross-linking polymer chains as Y, or Y—N—Z—N—[Y—N—Z—N]n—Y, wherein said cross linking polymer chains connect between one ammonium nitrogen atom in one polymer chain, and another ammonium nitrogen atom in another polymer chain and (iii) along pendant polymer chains as Y—N—Z—[N—Y—N—Z]n—N wherein said pendant chains originate at ammonium nitrogen atoms in other polymer chains, wherein n has a value from 0 to any higher integer,
• wherein group Y is an n-alkylene group or an alkyl substituted n-alkylene group, wherein said n-alkylene group or said alkyl substituted n-alkylene group has from 2 to at least 20 carbon atoms;
• and
• group Z is a hydrocarbylene group containing from 2 to 50 carbon atoms, said hydrocarbylene group optionally substituted with one or more hydroxyl, ether, amino, thioether, keto, ester, silyl group or heterocyclic rings;
• and at least 25% of the ammonium nitrogen atoms are secondary ammonium nitrogen atoms,
• with the result that said PFAS molecules are absorbed into said at least one crosslinked polymeric ammonium salt.