Reinforcement of single-walled carbon nanotube bundles by intertube bridging.
During their production, single-walled carbon nanotubes form bundles. Owing to the weak van der Waals interaction that holds them together in the bundle, the tubes can easily slide on each other, resulting in a shear modulus comparable to that of graphite. This low shear modulus is also a major obstacle in the fabrication of macroscopic fibres composed of carbon nanotubes. Here, we have introduced stable links between neighbouring carbon nanotubes within bundles, using moderate electron-beam irradiation inside a transmission electron microscope. Concurrent measurements of the mechanical properties using an atomic force microscope show a 30-fold increase of the bending modulus, due to the formation of stable crosslinks that effectively eliminate sliding between the nanotubes. Crosslinks were modelled using first-principles calculations, showing that interstitial carbon atoms formed during irradiation in addition to carboxyl groups, can independently lead to bridge formation between neighbouring nanotubes.
Institute of Physics of Complex Matter, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
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A
Kis
G
G
Csányi
J-P
JP
Salvetat
Thien-Nga
TN
Lee
E
E
Couteau
A J
AJ
Kulik
W
W
Benoit
J
J
Brugger
L
L
Forró
D001610:Beta Particles; D003432:Cross-Linking Reagents; D008854:Microscopy, Electron; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure; D013718:Tensile Strength
D003432:Cross-Linking Reagents; D037742:Nanotubes, Carbon