Dispersing multi-walled carbon nanotubes with water–soluble block copolymers and their use as supports for metal nanoparticles

Oxidized multi-walled carbon nanotubes (MWCNTs) were dispersed in aqueous and organic solvents by non-covalent modification with a double-hydrophilic block copolymer, poly(ethylene oxide)-b-poly [2-(N,N-dimethylamino)ethyl methacrylate] (PEO-b-PDMA). The PDMA segments were anchored onto the surface of the oxidized MWCNTs through multi-site zwitterionic interactions between the amino and the carboxyl groups while the PEO segments formed corona to promote the solubility of MWCNTs in different solvents. FT-IR and 1H NMR spectroscopy gave structural information on the resulting composite, supporting the successful modification. Thermal gravimetric analysis showed that the grafting yield could reach 26%. UV/vis and transmission electron microscopy provided direct evidence for the individual dispersion. The resulting modified MWCNTs could find broad spectrum of applications. As an example, Au and Pt nanoparticles were attached on the sidewall of the modified MWCNTs by using the amino groups of PDMA segments.