New dispersants for graphitic carbon and their sensor application

The electrical conductivity of nanospecies has attracted an increasing attention throughout the scientific community thanks to their utilization in sensors or smart devices like smartphones or customizable circuits. However, the effective dispersion of poorly soluble nanospecies is a crucial issue for the final application as the ultimate properties strictly depend on the formation of a percolative network. In this work, one kind of electrically conductive nanostructure based on multi-walled carbon nanotubes (MWCNTs) was selected and new surfactants were proposed to promote their effective dispersion in organic media. First, new perylene bisimides peripherally functionalized by crown ethers metal complexes (PeryCM) were synthesized and their mixtures with disentangled MWCNTs obtained via ultrasonication/centrifugation steps. The deposition of MWCNT/PeryCM dispersions on plastic film supporting gold electrodes allowed the fabrication of temperature sensors showing reproducible electrical resistances and typical semiconducting electrical transport, which depends on the nature of the metal. Second, an ethylene-propylene rubber (EPR) functionalised with maleic anhydride was utilized to disperse MWCNTs and promote their thermodynamic stabilisation. For this purpose, the polymer was opportunely modified with furfurylamine (FA), which foster the covalent and non-covalent anchoring of the graphitic carbon sidewalls. The obtained elastomeric nanocomposite showed the typical resistance variation with elongation, thus suggesting application as deformation sensors.