Elastic and electrically conductive carbon nanotubes/chitosan composites with lamellar structure

Porous carbon nanotubes/chitosan (CNTs/CHI) nanocomposites with very low density (∼0.02 g/cm3) were prepared by ice templating. The produced CNTs/CHI composites possess unidirectionally oriented lamellar structure with uniform layer thickness and channels in submicron and micron scale respectively. Due to this unique microstructure, the CNTs/CHI composites exhibit viscoelastic behavior under compression. With increasing fraction of CNTs, the recovery ability of CNTs/CHI composite increases and achieves the maximum (87% of original length) at a fraction of 0.48 vol.%, and then, decreases due to aggregation of CNTs. In addition, compared to pure chitosan scaffolds, electrical conductivity of CNTs/CHI composites are dramatically improved up to 8 orders of magnitude. The AC conductivities of CNTs/CHI composites follow the percolation scaling law with percolation threshold pc = 0.19 vol.% and scaling exponent t = 1.35. The low value of t = 1.35 suggests a quasi-two dimensional charge transport pathway in the composites.