Bulk Dispersion of Single-Walled Carbon Nanotubes in Silicones using Diblock Copolymers

The interactions of a series of poly(3-decylthiophene)-block-polydimethylsiloxanes (P3DT-b-PDMS) with single-walled carbon nanotubes (SWNTs) are investigated. The formation of supramolecular complexes of P3DT-b-PDMS with SWNTs is studied in THF, toluene, xylenes, and CHCl3, and the resulting complexes are characterized by UV-Vis-NIR absorption and fluorescence spectroscopy. The P3DT-b-PDMS-SWNT and P3DT-SWNT complexes are further incorporated into a commercially available silicone rubber formulation. Percolation thresholds of <0.02% (P3DT-b-PDMS-SWNT) and <0.05% (P3DT-SWNT) are measured. A decrease in the percolation threshold when using the block copolymer for nanotube dispersion is observed, suggesting that the presence of a covalently-linked PDMS block improves SWNT distribution in the silicone elastomer and allows a percolation network to form at low SWNT loadings. In addition, it is found that entanglement of the silicone block of P3DT-PDMS with bulk silicones results in anchoring of the nanotubes within the composite, and leads to reversible conductivity changes upon repeated stretching and relaxation. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 265-273