Reductive dissolution of supergrowth carbon nanotubes for tougher nanocomposites by reactive coagulation spinningElectronic supplementary information (ESI) available: Supplementary data (SEM, AFM line profiles, Raman spectra, TGA), schematic of spinning equipment, full tabulation of mechanical data, discussions and calculations of critical length reinforcement and dielectric properties. See DOI: 10.1039/c7nr00734e

Long single-walled carbon nanotubes, with lengths >10 μm, can be spontaneously dissolved by stirring in a sodium naphthalide N , N -dimethylacetamide solution, yielding solutions of individualised nanotubide ions at concentrations up to 0.74 mg mL −1 . This process was directly compared to ultrasonication and found to be less damaging while maintaining greater intrinsic length, with increased individualisation, yield, and concentration. Nanotubide solutions were spun into fibres using a new reactive coagulation process, which covalently grafts a poly(vinyl chloride) matrix to the nanotubes directly at the point of fibre formation. The grafting process insulated the nanotubes electrically, significantly enhancing the dielectric constant to 340% of the bulk polymer. For comparison, samples were prepared using both Supergrowth nanotubes and conventional shorter commercial single-walled carbon nanotubes. The resulting nanocomposites showed similar, high loadings ( ca. 20 wt%), but the fibres formed with Supergrowth nanotubes showed significantly greater failure strain (up to ∼25%), and hence more than double the toughness (30.8 MJ m −3 ), compared to composites containing typical ∼1 μm SWCNTs. Supergrowth CNTs are individualised in NaNp/DMAc and incorporated into nanocomposite fibres with increased toughness without decreasing strength or modulus.