Highly stretchable dielectric nanocomposites based on single-walled carbon nanotube/ionic liquid gels

We fabricated a highly stretchable dielectric composite using ionic liquid-based single-walled carbon nanotube gel (IL-SWCNT) as a dielectric filler and polydimethylsiloxane (PDMS) as an elastomer matrix. Transmission electron microscopy images showed that the SWCNTs were highly exfoliated and dispersed in the polymer matrix due to the addition of the ionic liquid (IL). The dielectric constant at 100 Hz of the IL-SWCNT/PDMS composite containing 1.6 wt% SWCNTs was twice that of the SWCNT/PDMS composite without IL, and the dielectric loss was one fifth that of the SWCNT/PDMS composite. In addition, the elastic modulus of the IL-SWCNT/PDMS composite was significantly lower (0.36 MPa at a strain of 20%) and the strain at break was higher (350%) compared to the corresponding values of the SWCNT/PDMS composites due to the plasticizer effects of the IL. These results provide the first feasibility study of the use of IL as both an exfoliation agent and a plasticizer in an effort to simultaneously improve the dielectric and mechanical properties of CNT-filled dielectric elastomers.