Functionalization of Single-Walled Carbon Nanotubes with End-Capped Polystyrene via a Single-Step Diels-Alder Cycloaddition

A facile, single-step, [4+2] Diels-Alder cycloaddition reaction for the surface functionalization of single-walled carbon nanotubes (SWNTs) with end-capped polystyrene chains is presented. The thermal cycloaddition reaction took place at high temperature (similar to 230 degrees C) without any catalyst between the sp(2) network of carbon nanotubes, which acted as dienophile, and the diphenylethylene 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 desorption/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).

Automated summary

A facile method for surface functionalization of single-walled carbon nanotubes with end-capped polystyrene chains was developed, involving a thermal cycloaddition reaction and anionic polymerization. Successful synthesis and quantitative end-capping reaction were confirmed by various analytical methods. The presence of thin polystyrene film on the CNT surface was directly evidenced by TEM and AFM.