Functionalization of single-walled carbon nanotubes with end-capped polystyrene via a single-step diels–alder cycloaddition

Abstract

A facile, single-step, [4+2] Diels–Alder cycloaddition reaction for the surface functionaliza-tion of single-walled carbon nanotubes (SWNTs) with end-capped polystyrene chains is presented. The thermal cycloaddition reaction took place at high temperature (~230◦ C) without any catalyst between the sp2 network of carbon nanotubes, which acted as dienophile, and the diphenylethy-lene cyclobutene (DPE-CB) terminal group of the polystyrene chain. Anionic polymerization was employed for the synthesis of the polystyrene macromolecule, and successful and quantitative end-capping reaction with the DPE-CB molecule was confirmed by matrix-assisted laser desorp-tion/ionization time of flight mass spectroscopy. Thermogravimetric analysis revealed the wt % of the grafted macromolecule on the CNT surface as well as the grafting density of the polymer chains on the SWNTs (0.027 chains nm−2). Direct evidence for the surface functionalization and the presence of thin polystyrene film was obtained by transmission electron microscopy (TEM) and by atomic force microscopy (AFM).