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

• Main Authors: Maria-Malvina Sathouraki, Christos Pantazidis, Emmanouil Mygiakis, Apostolos Avgeropoulos, Georgios Sakellariou
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Polymers
• Subjects: single-walled carbon nanotubes; [4+2] Diels–Alder cycloaddition; surface functionalization; anionic polymerization
• Online Access: https://www.mdpi.com/2073-4360/13/7/1169

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 (~230 °C) without any catalyst between the <i>sp</i>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).