Super‐Compressible Foamlike Carbon Nanotube Films.

Abstract

Nanotechnology V 1505Super-Compressible Foamlike Carbon Nanotube Films. -Freestanding films of vertically aligned, multiwalled carbon nanotubes produced by chemical vapor deposition with ferrocene and xylene as the precursors exhibit super-compressible foamlike behavior. Under compression, the nanotubes collectively form zigzag buckles that can fully unfold to their original length upon load release. The nanotube films show much higher compression strength, recovery rate, and sag factor than conventional low-density flexible foams. The lightweight, highly resilient nanotube films may be useful as compliant and energy-absorbing coatings. -(CAO*, A.; DICKRELL, P. L.; SAWYER, W. G.; GHASEMI-NEJHAD, M. N.; AJAYAN, P. M.; Sci. (Washington, D. C., USA) 310 (2005) 5752, 1307-1310; Dep. Mech. Eng., Univ. Hawaii, Honolulu, HI 96822, USA; Eng.) -W. Pewestorf 09-235

Biomimetic superelastic graphene-based cellular monoliths

“…According to the literature 13 , all the existing carbon foams and porous carbons except for those made of fibrous carbon 15,17,19,21 or graphitic ribbons 20 are prone to failure in a brittle manner when subjected to macroscopic deformation. Previous studies suggest that when foam made of mono-or very few layers of graphene is severely compressed, the intersheet van der Waals adhesion would overwhelm the elastic energy stored, preventing elastic recovery 13,37 .…”

“…However, as with most of the existing porous carbon materials 13 , the resulting graphene monoliths are generally brittle and have small recoverable deformation before failure unless they are infiltrated with an elastomeric polymer 5 or grown on pre-formed carbon nanotube aerogels 14 . Superelasticity that has been observed in foams made of carbon-based tubular or fibrillar nanostructures [15][16][17][18][19][20][21] has not been achieved in foams solely based on graphene sheets. Indeed, as the specific elastic bending stiffness of a sheet-like structure is known to be intrinsically inferior to that of its tubular or fibrillar counterparts 22 , previous analysis 13 suggests that it would be highly challenging to realize superelasticity in graphene foams.…”

Local Relative Density Modulates Failure and Strength in Vertically Aligned Carbon Nanotubes

“…Figure S1 highlights four literature examples of the differences in the mechanical response of various CVD-VACNT micro-pillars subjected to compression. Note in particular the higher stiffness and strength of the VACNTs grown using the floating catalyst technique in Fig S1a, 5 as compared to the ones grown using the fixed catalyst method (Figs. S1b, 3 S1c 6 and S1d 7 ).…”

“…Here the first buckle generally nucleates close to the substrate, and each subsequent lateral collapse event initiates only after the preceding one was completed, thus sequentially collapsing the entire structure. 3,[5][6][7] We are unaware of any literature report that suggests a different buckling sequence (such as top-to-bottom or otherwise) for VACNT pillars under compression. VACNT micro-pillar 6 and (d) 50 µm × 60 µm (diameter × height) VACNT micro-pillar.…”

“…2 in the manuscript), where the first buckle is nucleated close to the substrate and each subsequent buckle initiates above the previous one. 5,7 If the sample is unloaded from a maximum compression of ~70% strain, the top third of the pillar remains virtually unscathed (Fig. S9b, left panel), and the buckle closest to the pillar-top is always the last one to form (Fig.…”