Interface localization of carbon nanotubes in blends of two copolymers

The localization of unpurified and unfunctionalized multiwall carbon nanotubes (MWNTs) in an immiscible polymer blend has been studied. The sea-island morphology of ternary blends of a copolyamide 6/12 (PA6/12), a copolymer of ethylene and methyl acrylate (EMA) and MWNTs was studied by SEM and TEM. Depending on the mixing sequence, the MWNTs are localized either in the PA phase or at the interface. The localization of the MWNTs is determined both by the thermodynamics of the minimization of the interfacial energies and by a partial (irreversible) adsorption of the macromolecules of the first copolymer in contact with the MWNTs during the mixing step. The adsorption phenomenon is proved by TGA, EELS, modification of the MWNTs and decantation tests. It is attributed to non-covalent and non-specific interactions occurring between the CH groups of the polymers and the MWNTs.