Preparation of poly(ethylene glycol)-b-polyacrylonitrile block copolymer functioned multi-walled carbon nanotubes by “graft onto” and “graft from”

摘要

Multi-walled carbon nanotubes (MWNTs) were oxidized with concentrated HNO3 and H2SO4 to introduce carboxylic groups. Grafting of poly (ethylene glycol) (PEG) onto carbon nanotubes (MWNTs-g-PEG) was achieved by the direct condensation reaction of carboxyl groups on the acids-treated carbon nanotubes surface with hydroxyl groups of PEG using N,N-dicyclohexylcarbodiimide (DCC) and 4-dimethylaminopyridine (DMAP) as a condensing agent. Then, Ce4+/hydroxyl redox system initiated acrylonitrile (AN) from MWNTs-g-PEG to get poly(ethylene glycol)-b-polyacrylonitrile (PEG-b-PAN) block copolymer functioned MWNTs [MWNTs-g-(PEG-b-PAN)] under the acidic condition. As-prepared block copolymer functionalized MWNTs were characterized with FTIR, TEM and TGA. TGA suggested that the grafted ratio of the block copolymer on the MWNTs. It could be observed that the polymer shell is vividly impinged on the outer wall along the tubes. The dispersion experiments showed that the solubility of the modified MWNTs in DMF had been improved greatly.