Hairy Carbon Nanotube@Nano-Pd Heterostructures: Design, Characterization, and Application in Suzuki C−C Coupling Reaction

Abstract

Poly(glycidyl methacrylate), PGMA, was prepared via ATRP in bulk solution, and its epoxy groups were further acid-hydrolyzed in order to obtain a polymer with glycerol moieties (noted POH). The POH chain end C−Br bonds were subjected to a nucleophilic attack by NaN₃, resulting in azide-terminated POH (POH−N₃). The CNTs were modified by in-situ-generated alkynylated diazonium cations from the para-alkynylated aniline of the formulas H₂N−C₆H₄−C≡C−H, yielding CNT−C₆H₄−C≡C−H nanotubes. The azide-functionalized polymer POH−N₃ was clicked to the alkynyl-modified CNTs giving CNT@POH hybrids, which were further subjected to an oxidation resulting in carboxylated polymer-modified CNTs (noted CNT@PCOOH). The as-designed hairy CNTs served as efficient platforms for the in-situ synthesis and massive loading of 3 nm sized palladium nanoparticles (NPs). The CNT@PCOOH@Pd heterostructures prepared so far exhibited an efficient catalytic effect in the C−C Suzuki coupling reaction and were regenerated up to four times without any significant loss of catalytic activity.