Coupling activity of ionic liquids between diene elastomers and multi-walled carbon nanotubes

In order to ensure better rubber/multi-walled carbon nanotube (MWCNT) compatibility and to enhance the dispersibility; a series of ionic liquids has been tested in regard to an improved interaction between rubber and carbon nanotubes. We found that in the presence of especially one ionic liquid, namely, 1-allyl-3-methyl imidazolium chloride, for the blend of solution-styrene-butadiene and polybutadiene rubber, used as basic elastomer, a three fold increase of tensile strength was achieved with only similar to 3 wt.% MWCNT loading. At this low concentration of MWCNTs the sample can be stretched up to 456% without mechanical failure. The use of this ionic liquid additionally results in higher electrical conductivity (10(-2) S cm(-1)) at low concentration (< 3 wt.%) of MWCNTs. Dynamic mechanical analysis confirmed the specific interaction of CNTs and diene rubber chains by showing an extra relaxation process at relatively higher temperature (similar to T-g + 130 K) in the temperature sweep measurements. Raman spectroscopic analysis also supported the specific interaction between MWCNTs and rubber molecules with the help of 1-allyl-3-methyl imidazolium chloride. Transmission electron microscopic images confirm the good dispersion of the MWCNTs along with a 'cellular'-like structure of the CNTs in the rubber matrix. (C) 2009 Elsevier Ltd. All rights reserved.