Effect of Chemical Modification on Functionalization of Carbon Nanotubes by Poly (ethylene glycol)

Poly(ethylene glycol)-grafted multi-walled carbon nanotubes were prepared by acylchloride-amidation reaction and EDC/NHS(N-ethyl-N-(3-dimethylaminopropyl)carbodiimide hydrochloride/N-hydroxysuucinimide)activated amidation reaction.The obtained grafted MWNTs were characterized by FTIR,Raman,TEM,atomic force microscopy(AFM),TGA-DTA-DSC,and UV-Vis spectroscopy.Experimental results indicate that MWNTs could be functionalized well by both the acylchloride-amidation and EDC/NHS activated amidation reactions,but the EDC/NHS activated amidation reaction is more efficient.The EDC/NHS method improves greatly the grafted rate and the efficiency in using of the carboxylic acid moieties at the defect sites of MWNTs.On the basis of thermogravimetric analysis,the grafted rate is estimated to be 30% for EDC/NHS activated amidation reaction,but only 15% for acylchloride-amidation reaction.UV-Vis studies of these polymer-grafted MWNTs indicate a water solubility of about 1.19 mg·mL-1 for acylchloride-amidation reaction and 2 mg·mL-1 for EDC/NHS activated amidation reaction.