A method for wet spinning of alginate fibers with a high concentration of single-walled carbon nanotubes

A method is described for the wet spinning of alginate fibers with a loading of single-walled carbon nanotubes as high as 23 wt%. Electrostatic assembling of polyelectrolytes and nanotubes coated with sodium dodecyl sulfate is exploited by using calcium as a cross-linking agent. The Young’s modulus of these fibers depends non-monotonically on nanotube concentration which is explained using Halpin-Tsai and Voigt models. Scanning electron microscope micrographs and resistivity analysis of the fibers suggest that the nanotube-alginate system undergoes a morphological transition from a composite structure of discrete nanotube bundles embedded in an alginate matrix to a complex continuous structure consisting of a nanotube network interwoven into a macromolecular network of alginate. The nanotube-alginate fibers have unprecedented high flexibility and a very high electrical conductivity similar to semimetals (between germanium and carbon).