Increasing electrical conductivity of PMMA-MWCNT composites by gas phase iodination

A highly electrical conductive multi-walled carbon nanotubes based polymer composite is fabricated by iodine doping. Selective localization of carbon nanotubes in polymethyl methacrylate was obtained by intensive dry mixing of polymer and nanotubes powders followed by hot pressing. The electrical conductivity of the materials was significantly increased (10-100%) when the composites were treated with iodine by the gas phase. The electrical conductivity of the materials was significantly increased because of MWCNTs addition from the value not higher than about 10-15 to about 10-2 S/cm. The addition of iodine leads to an additional increase in electrical conductivity by 10-100%, depending on the content of MWCNTs. It is interesting to note that a more effective increase in electrical conductivity is observed at low MWCNTs concentrations. An interesting result of the work is the presentation of the fact that iodine is uniformly absorbed in the bulk of the composite filled with nanotubes; in the case of an unfilled polymer, iodine is deposited only on the sample surface. The percolation nature of the conductivity of the investigated composites was found and the percolation threshold was calculated. It was shown that the percolation threshold does not significantly change after iodination. Thus, in this work, we have shown the possibility of simple technology for producing composites with a spatial localized distribution of carbon nanotubes, providing high conductivity (2.86 x 10-2 S/cm) and a low percolation threshold (about 0.37% vol.) at the MWCNTs content of 1.55% vol.

Automated summary

A highly electrical conductive multi-walled carbon nanotubes based polymer composite was fabricated by iodine doping, resulting in a significant increase in electrical conductivity of the materials. The increase in conductivity was mainly attributed to the addition of MWCNTs and the effect of iodine treatment on the composites.