Abstract: A functionalized polymeric composition having a backbone, and at least one compound having at least one thiol-functional group or at least one amino-functional group. A method of preparing a functionalized polymeric composition, the method (i) providing a backbone; and (ii) reacting the backbone with an amino-thiol compound to obtain a functionalized polymeric composition. A method for removing metals from an aqueous stream, the method (i) providing a functionalized polymeric composition; (ii) adding the functionalized polymeric composition to an aqueous stream comprising a plurality of metal contaminants; (iii) allowing the polymeric composition to react with the metal contaminants to form an insoluble complex; and (iv) allowing the insoluble complex to settle out of solution or remove the insoluble complex through filtration.