Grafting of thermoresponsive polymer from the surfaceof functionalized multiwalled carbon nanotubes via atom transfer radical polymerization

Multiwalled carbon nanotubes were oxidized with concentrated HNO3 and H2SO4 to introduce carbox-ylic groups onto carbon nanotubes surfaces. The oxidized carbon nanotubes were reacted subse-quently with thionyl chloride and 2-Hydroxylethyl-2′-bromoisobutyrate, producing MWNT-based macroinitiators, MWNT-Br, for the atom transfer radical polymerization of (N-isopropylacrylamide). FTIR, XPS, 1H NMR, Raman and TGA were used to characterize the resulting products and to determine the content of the water-soluble poly (N-isopropylacrylamide) chains in the product. The MWNTs grafted with PNIPAM chains have good solubility in distilled water; THF and CHCl3. TEM images of the samples provide direct evidence for the formation of a nanostructure that MWNTs coated with polymer layer. The produced MWNT-g-PNIPAM has a PNIPAM shell, which is very sensitive to the change of temperature. This method would open a door for the fabrication of novel functional carbon nanotube-based nano-materials or nanodevices with designable structure and tailor-made properties.