Functionalisation of multi-walled carbon nanotubes by esterification method for poly(ethylene)glycol attachment and their characterization

Abstract

In this study, we have successfully functionalised multi-walled carbon nanotubes (MWCNT) surfaces with poly(ethylene)glycol (PEG) via an esterification method in which the oxygenated functional groups are created by chemical oxidations with a mixture of nitric acid and sulfuric acid solutions (ratio of 1:3, v/v), and then it is reacted with functional groups of PEG. Different techniques including FE-SEM, TEM, EDS, FT-IR spectrometry, Raman spectroscopy and TGA are applied to identify the characteristics of MWCNTs. The effects of catalyst and different mass ratios of PEG:MWCNTs on the characteristics of MWCNTs are investigated for the first time. The TGA analysis indicates that when the mass ratio of PEG:MWCNTs is 140:1, the highest weight loss of 30.86 wt% is obtained. Additionally, an increase in the amounts of catalysts decreases the content of PEG attached on the nanotubes. The catalyst of 0.3 ml H2SO4 and the mass ratio of PEG:MWCNTs = 140:1 demonstrates to be the most effective for PEG functionalised MWCNTs. It can be chosen as the best experimental conditions to perform PEG functionalised MWCNTs.