Fig. 2: Mechanical properties.

a Tensile responses of CNAs with their porosity ranging from 76% to 91%. b Compressive stress-strain curves of CNAs with various porosity levels. c Tensile moduli of CNAs as a function of their density, obtained from experimental characterization and theoretical fitting. d Fracture energies of CNAs as a function of their porosity. e Anisotropic tensile responses of an CNA sample with highly oriented fibrils, measured from the directions parallel and perpendicular to the fibril orientation, respectively. f Toughness and specific tensile modulus of CNAs, as compared with other polymeric aerogels with high mechanical properties. The toughness was calculated by integrating the tensile stress-strain curves from various materials (Supplementary Table 1).