One-step photo-induced modification of carbon nanotubes via polymeric diazonium chemistry

Diazonium chemistry serves as a versatile and facile approach for surface modification. In this work, we propose a strategy of one-step photo-induced modification of carbon nanotubes (CNTs) with polymeric diazonium salts. The PEGylation process was conducted with diazonium-terminated poly(ethylene glycol) (mPEG-N2+) or PEG-based block polymeric diazonium salts (PEG-b-PSN2+) under irradiation with 275 nm ultraviolet light. The covalent functionalization of PEG-CNTs was verified by transmission electron microscopy, thermogravimetric analysis and Fourier-transform infrared spectroscopy. A thorough investigation involving the impact of varied functionalities of PEG-based polymeric diazonium salts on the PEGylation rate as well as polymer content is presented. It was concluded that the block copolymer with moderate functionality showed great potential in this strategy. On the other hand, hydrophobic modification with PS-based block polymeric diazonium salts (PS-b-PSN2+) was also carried out successfully. Herein, we present a novel strategy for the preparation of CNT–polymer composites in a one-step route, notable for its universality in both aqueous and organic solutions.