Deposition of copper nanoparticles on ozone pre-treated MWCNTs in fluidized-bed CVD

In the field of aeronautics, the mass reduction of the on-board electronic equipment packaging is of major importance to make planes greener. To produce lighter packaging while keeping their electrical and thermal evacuation capacities and mechanical properties, a new composite material combining carbon nanotubes (CNTs) and polymer matrix represents a promising alternative to aluminium. The aim of this work is to improve the electrical and thermal conductivities of Multi-Walled CNTs, and consequently those of the final composite material, by depositing homogeneously dispersed nanoparticles (NPs) of copper on the MWCNT surface. Prior to copper deposition, Graphistrength®C100 MWCNTs tangled in porous balls of ca. 400 micrometres were oxidised in fluidized bed using a gaseous mixture of ozone, water vapor, and oxygen in order to increase their surface reactivity by grafting oxygen-containing groups and creating moderate structural defects uniformly on the MWCNT surface. 100 g of MWCNTs were treated for each experiment in a fluidization reactor at ambient temperature and atmospheric pressure. The same reactor was used to deposit copper NPs from Cu(acac)2 between 250°C and 280°C at atmospheric pressure, on both raw and pre-treated MWCNTs. On the raw MWCNTs, polycrystalline Cu NPs of several hundreds of nanometres are only present at the MWCNT ball surface over ~40 micrometre depth. With pre-treatment, the deposition of (much smaller, 20-50 nm) polycrystalline Cu nanoparticles occurs more uniformly both over the MWCNT surface and deeper inside the balls. The work demonstrates the upscalability of the process as a reasonably green and low cost technology.