An effective self-assembly of colloidal Au nanoparticles (NPs) on functionalized MWNTs was proposed, using a photochemical method by seed-mediated controllable growth to obtain Au NPs with different sizes. The method based on functionalized MWNTs with carboxyls were chemically modified by mercaptoacetic acid of bifunctional groups so as to connect mercapto groups, subsequently, Au NPs with different sizes were anchored on the sidewalls of functronaliged MWNTs by means of covalent binding action between Au NPs and -SH, respectively, and then fine Au/MWNTs hybrid materials were obtained. According to various characterizations for colloidal Au NPs, Au/MWNTs composites and self-assembled process by UV-vis spectrum, TEM and XRD technologies, the effect of the Au NP sizes on the self-assembly of functronaliged MWNTs was investigated in detail. The results show that Au NPs with well dispersion in the size range 2.5～5.2 nm can finely assemble on the sidewalls of functronaliged MWNTs with a mean diameter about 20 nm. At the same time, the driving forces of the chemical modification and the MWNTs-mediated self-assembly of Au NPs were discussed.

Key words: multiwalled carbon nanotubes, gold nanoparticles, covalent binding, self-assembly