Synthesis of Water-soluble Poly(vinyl alcohol)-grafted Multi-walled Carbon Nanotubes

A facile method for preparing waster-soluble poly(vinyl alcohol)-grafted multi-walled carbon nanotubes (PVA-grafted MWNTs) was developed. Well-defined poly(vinyl acetate) chains end-capped by a cobalt(II) acetylacetonate (Co(acac)(2)) complex [PVAc-Co(acac)(2)] were synthesized by the cobalt-mediated radical polymerization (CMRP) of vinyl acetate. PVAc macroradicals generated by the homolytic cleavage of the carbon-cobalt (C-Co) bonds of PVAc-Co(acac)(2) chains were then grafted directly to the MWNTs via radical addition reactions in dimethyl sulfoxide (DMSO) at 50 degrees C. The amount of the PVAc grafted onto the surface of the MWNTs decreased with increasing molecular weight of PVAc-Co(acac)(2). Hydrolysis of the grafted PVAc finally yielded PVA-grafted MWNTs, which showed good solubility in water. Surface functionalization of the MWNTs was confirmed by H-1 NMR spectroscopy, FTIR spectroscopy and TEM.