Dielectric relaxation and rheological properties of single-walled carbon nanotubes reinforced poly(3-octylthiophene-2,5-diyl)

Abstract

Polymer nanocomposites consisting of single-walled carbon nanotubes (SWCNTs) and poly(3-octylthiophene-2,5-diyl) (P3OT) were prepared at different SWCNT loadings to investigate the influence of SWCNT content on the structure, dielectric and rheological properties of P3OT host. The dielectric parameters and dielectric relaxation behavior were investigated as a function of SWCNT loadings and frequency. Dielectric results reveal that SWCNTs enhance the polar character of P3OT host, shift the peak maximum of loss tangent toward higher frequency values and increase the alternating current conductivity especially above the percolation threshold point. Besides, the rheological properties of SWCNT-P3OT composites were also investigated to realize the effect of SWCNT content on the complex viscosity, storage and loss moduli at different frequency values. The obtained results reveal that nanocomposites become electrically percolated at 0.44 wt% SWCNTs, while the rheological percolation threshold was found at 0.5 wt%. Additionally, this study showed that the relaxation behavior in SWCNT-P3OT composites is mainly due to the viscoelastic relaxation process. Moreover, at high level of SWCNT loadings, the nanotubes became more interconnected to form network like structures in the P3OT host. Finally, results obtained from structure–property analysis reveal that the addition of SWCNTs to P3OT host reduced the vibrational freedom of the polymer chains as a consequence of the intercalation of the polymer matrix into the nanotubes.