Described herein is method of functionalizing fluorinated polymers, wherein a reaction compound is grafted onto a fluorinated polymer, wherein the fluorinated polymer comprises at least one Br, I, and Cl group and is free of —CH2CH2— linkages. In one embodiment, the functionalized fluorinated polymer comprises a perfluorinated polymer backbone with pendent groups therefrom is disclosed, wherein at least one pendent group is according to formula I: where Rf is a bond, or a divalent perfluorinated group, optionally comprising at least one in-chain ether linkage; Z is I, Br, or Cl; and X comprises a functional group selected from the group consisting of an alcohol; phosphorous acid and salts thereof; phosphoric acid and salts thereof; a silane; an amine; an amide; a hydrocarbon, optionally comprising an in-chain oxygen, nitrogen, or sulfur linkage; a carboxylic acid and salts thereof; an ester; a sulfonyl fluoride, a sulfonic acid and salts thereof; and combinations thereof. Such functionalized fluorinated polymers may be used in coating compositions.