Factors affecting the dispersion of MWCNTs in electrically conducting SEBS nanocomposites

The accessible concentration of exfoliated and undamaged multi-walled carbon nanotubes (MWCNTs) in polymer nanocomposites is an essential issue to the future of these materials. In this work, we report two methodologies directed at obtaining electrically conducting poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) nanocomposites with different MWCNT contents. The first depends on the time modulation of ultrasonication of toluene mixtures, whereas the second relies on the use of alkyl-functionalized MWCNTs (f-MWCNTs). UV–vis spectroscopy investigations and thermogravimetric analyses allowed the quantification of exfoliated CNTs incorporated in the SEBS mixture. TEM micrographs denoted that a prolonged sonication time (40 min) induced an extensive MWCNTs degradation (average length decreased of 40%), which affected the electrical conductivity of the nanocomposites. The f-MWCNTs appeared to be more effective in preparing SEBS nanocomposites due to the higher dispersion efficiency, negligible nanotube degradation and higher electrical conductivity. The temperature dependence of the resistance of the SEBS/MWCNT system was investigated in the range 20–60 °C to explore its potential for sensor development.