Composites of single-walled carbon nanotubes and styrene-isoprene copolymer latices

Composites of a styrene-isoprene copolymer and SWNTs were prepared by emulsion and miniemulsion polymerization in the presence of SWNTs, as well as by mixing dispersed SWNTs with a styrene-isoprene copolymer latex after polymerization. For the former, the surfactant was displaced from SWNTs to monomer droplets leading to SWNT aggregation. Mixing dispersed SWNTs with latex after reaction was able to preserve SWNT dispersion and gave a polymer composite with an electrical percolation threshold of 0.2%. Dynamic mechanical measurements of film samples in tension showed that the composites had a measurable modulus above T-g, indicating entanglement formation. 4) The modulus above T-g was strongly temperature dependent, confirming shear measurements that have shown entanglements in SWNT/polymer composites involve both polymer and nanotubes.