Modification of carbon nanotubes with a nanothin polydopamine layer and polydimethylamino-ethyl methacrylate brushes

The work reports on a nondestructive pathway to produce polymer brush modified carbon nanotubes (CNTs) through surface-initiated polymerization followed by nanoparticle uploading. First, polydopamine layers with high surface coverage were formed on CNTs by spontaneous oxidative polymerization of dopamine. These were then used as the reactive layer for subsequent initiator attachment and brush grafting. Atom transfer radical polymerization of dimethylamino-ethyl methacrylate was initiated from the initiator layer, resulting in the formation of uniform polydimethylamino-ethyl methacrylate (PDMAEMA) brushes on the CNT surface. These were further quaternized by the reaction with CH₃I to form cationic Quaternized-PDMAEMA brushes (Q-PDMAEMA). The reversible solubilities of PDMAEMA- and Q-PDMAEMA-modified CNTs were achieved by switching between different solutions. Palladium nanoparticles were attached onto the CNTs using Q-PDMAEMA mediated anion exchange followed by in situ reduction using NaBH₄. The electrocatalytic behavior of the material was studied using an electrochemical method.