Synthesis of amine-functionalized block copolymers for nanopollutant removal from water

Polyamines are rare in literature owing to increased reactivity, sensitivity to air and moisture, low stability, and processing difficulties. Here, we report the synthesis and characterization of highly processable polyamines and use them for the removal of dissolved metallic nanoparticles from water. Three amphiphilic block polyamines such as poly(N-aminoethyl acrylamide-b-styrene), poly(N-aminopropyl acrylamide-b-styrene), and poly(N-aminoxylyl acrylamide-b-styrene) have been synthesized using atom transfer radical polymerization of ethyl acrylate and styrene followed by aminolysis of the acrylic block. The polymerization and properties of the polymers are studied using different physicochemical techniques. Surface morphology of films prepared from these block copolymers by dissolving in different solvents such as chloroform, tetrahydrofuran and N,N- dimethylformamide, and drop-casting polymers on a glass substrate show interesting porous films and spherical nanostructures. In addition, the amine-functionalized block copolymers have been used for the removal of nanoparticles from water and show high extraction efficiency toward silver (Ag) and gold (Au) nanoparticles. All three amine-functionalized block copolymers show higher extraction capacities (Q_e) toward Au NPs (50-109 mg g^-1) and Ag NPs (99-117 mg g^-1). Our approach allows us to make amine-functionalized block copolymers which are stable in air and can be easily processed in nonpolar solvents.