Polymer, Vol.48, No.15, 4352-4360, 2007
Preparation of multi-walled carbon nanotubes grafted with synthetic poly(L-lysine) through surface-initiated ring-opening polymerization
A surface-initiated ring-opening polymerization approach was used to functionalize multi-walled carbon nanotubes (MWNTs) with linear poly(L-lysine) (PLL). The oxidized MWNTs, which resulted from the treatment of MWNTs with mixed concentrated sulfuric acid and nitric acid, were converted into amino-functionalized MWNTs (MWNT-NH2) by the amidation of carboxylic group on MWNT surface with excess 1,6-diaminohexane. Surface-initiated ring-opening polymerization of epsilon-(benzyloxycarbonyl)-L-lysine N-carboxyanhydride with MWNT-NH2 as the initiator resulted in MWNTs grafted with poly(epsilon-(benzyloxycarbonyl)-L-lysine) (MWNTg-PLys(Z)). After the acidolysis of benzylcarbamate group of the grafting poly(epsilon-(benzyloxycarbonyl)-L-lysine) chain, water-soluble MWNTs grafted with PLL (MWNT-g-PLL) were obtained. The successful grafting was confirmed by Fourier transform infrared spectroscopy, thermal gravimetric analysis, X-ray photoelectron spectroscopy, elemental analyses, high-resolution transmission electron microscopy (HRTEM) and field-emission scanning electron microscopy. HRTEM indicates that MWNTs were enveloped by PLL layer. The as-prepared MWNT-g-PLys(Z) and MWNT-g-PLL exhibited excellent ability to disperse homogeneously in THF and water, respectively. (c) 2007 Elsevier Ltd. All rights reserved.