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Mechanics of Nanostructures

Mechanics of Nanostructures (Conformational states of nanotubes & tensile-loading mechanics of CNTs) Prof. Rod Ruoff Department of Mechanical Engineering Northwestern University 2145 Sheridan Road Evanston, IL 60208-3111 r-ruoff@northwestern.edu http://bucky-central.mech.northwestern.edu/

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Mechanics of Nanostructures

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  1. Mechanics of Nanostructures (Conformational states of nanotubes & tensile-loading mechanics of CNTs) Prof. Rod Ruoff Department of Mechanical Engineering Northwestern University 2145 Sheridan Road Evanston, IL 60208-3111 r-ruoff@northwestern.edu http://bucky-central.mech.northwestern.edu/ NABIS Chicago August 2006 Support from the NSF, ONR, and NASA is appreciated

  2. Richard Piner Dmitry Dikin Xinqi Chen NUANCE staff member Sasha Stankovich Rod Ruoff Supinda Watcharatone Weiqiang Ding Terry Xu UNC-Charlotte Shaoning Lu Touchdown Technologies Robbie Cantrell PhD-MD Eric Zimney Inhwa Jung Kevin Kohlhaas Abel Thangawng The group Jae Chung U Wash-Seattle Geoffrey Dommett, Physics

  3. 1-D Nanostructures Single-wall carbon nanotube (SWCNT) Multi-wall carbon nanotube (MWCNT) TEM image of a multi-wall carbon nanotube SEM image of arc-grown MWCNTs from MER Corp. AZ.

  4. R. S. Ruoff, J. Tersoff, D. C. Lorents, S. Subramoney, and B. Chan, Radial deformation of carbon nanotubes by van der Waals forces. Nature, 364, 514-16 (1993). Mean values for inter-fringe distances: MWCNT B: 3.51 (outer) but 3.43 Angstroms (inner) MWCNT A 3.45 (outer) but 3.38 (inner)

  5. Single-walled carbon nanotube bundle comprised of SWCNTs with diameter ~ 1.4 nm. Thess et al, Science. Novel polygonized single-wall carbon nanotube bundles M J Lopez et al Phys Rev Lett 86 (14): 3056-3059 APR 2 2001 DWCNTs: M. Endo et al Nature 433, 476 (2005) Scale bar: 5 nm; measure of 5 DWCNTs present in this image, average diameters of CNTs (inner) and (outer) are 1.31 and 2.23 nm J. Tersoff and R. S. Ruoff, Structural properties of a carbon-nanotube crystal. Phys. Rev. Lett., 73, 676-9 (1994).

  6. Probing conformational states of MWCNTs. Embed in Formvar, deform at ~70 C Rod Ruoff, Rob LaDuca, Shekhar Subramoney, unpublished results

  7. 15-shell MWCNT Dong Qian, Wing Kam Liu, Shekhar Subramoney, and Rodney S. Ruoff, Effect of Interlayer Potential on Mechanical Deformation of Multiwalled Carbon Nanotubes, Journal of Nanoscience and Nanotechnology, 3(1/2), 185-191 (2003).

  8. Left: Relative H atom binding energies (squares), relative cohesive energies (circles), and relative electronic energies (triangles) for the highlighted atoms. The center atom along the line of highlighted atoms corresponds to an abscissa equal to zero. Right: Dependence of these energies on ‘POAV1’ pyramidalization angle. D. Srivastava, D. W. Brenner, J. D. Schall, K. D. Ausman, M. F. Yu and R. S. Ruoff, Predictions of enhanced chemical reactivity at regions of local conformational strain on carbon nanotubes: Kinky chemistry, J. Phys. Chem., B, 103, 4330-4337 (1999).

  9. Fracture Mechanics of One-Dimensional Nanostructures: outer shell of MWCNTs

  10. Piezoelectric Actuator Z-stage X-Y Stage Piezo bimorph X-Y stage Z stage Specimen/ Cantilever Holder Cantilever Holder Testing Tool: Nanomanipulator A home-built nanomanipulator is used to perform mechanics study inside vacuum chamber of ascanning electron microscope (SEM). Nanomanipulator inside vacuum chamber of FEI Nova 600 SEM (Ruoff group) Home-built nano-manipulator

  11. X-Y Stage soft cantilever L rigid cantilever Z Stage L+ s Setup: Nanoscale Tensile Test Atomic force microscope (AFM) cantilevers are used as manipulation tools and force-sensing elements. Tensile Test Schematic Experimental Setup MWCNT

  12. Stretching a chain Tensile Testing Contact Force Measurement • Carbon nanoparticle chain aggregates • Nanoparticle diameter: 25-35 nm • Chain length: ~ 2 m • Breaking Force: 42  25 nN • Tensile Strength: 40 -100 MPa • Elastic Modulus : 200 - 600 MPa • Particle Contact Force: 8 4 nN Nanoparticle Chain Aggregates Mechanics Mechanical properties of nanoparticle chain aggregates by combined AFM and SEM: Isolated aggregates and networks, collaboration with S. Friedlander Group, UCLA, submitted to Nano Letters.

  13. In situ Clamping - EBID Electron beam induced deposition (EBID) is the process of using a high-intensity electron beam to deposit structures on a scanned surface.EBID is commonly used to make clamps in situ inside SEM. EBID clamp Hydrocarbon molecules Exposure area EBID principle A CNT in contact with an AFM tip, before and after EBID clamping

  14. MWCNT: Carbon Nanotube Source Arc-grown Multi-wall Carbon Nanotubes (MWCNTs) from MER Corp. AZ. were studied in this work. A simple fractionation process was used to remove some impurities and increase nanotube concentration. SEM image of powdered cathode deposit core material with 30-40% MWCNT content from MER Corp. SEM image of separated MWCNTs on a silicon wafer, after fractionation.

  15. D  Inner shells Outer shell MWCNT: “Sword-in-sheath” Fracture Multi-wall carbon nanotubes fracture in a “sword-in sheath” manner during tensile test. Cross-sectional area: : inter-layer separation of graphite, 0.34 nm

  16. MWCNT: Diameter Measurement Cantilever holders were designed to hold a shortened AFM chip for nanotube diameter measurement in TEM. AFM cantilevers (a) AFM chip holder model (c) Gatan TEM straining holder (model 654) (d) SEM and TEM images of a MWCNT fragment attached to an AFM tip. (b) An AFM chip in the AFM chip holder

  17. MWCNT: Stress & Strain Measurements The whole tensile testing process was recorded by taking SEM images at each loading step.

  18. MWCNT: Tensile Testing Result Fracture Strength Elastic Modulus Average elastic modulus: ~ 910 GPa

  19. MWCNT: Multiple Loading (Tube #6) (1) (2) (3)

  20. SWCNT fracture mechanics… Collaboration with Jim Hone group, Columbia University Alan Cassell, NASA Ames

  21. SWCNT Sample Individual or small bundle of SWCNTs spanning across a trench (from Prof. Jim Hone’s group, Columbia Univ.)

  22. We wonder if you have n and m for this (these) tubes? This is the one that Weiqiang measured. Does Hone team know n and m? Notes accompanying samples sent

  23. Z Stage Tipless AFM cantilever X-Y Stage Tensile Testing Configuration Experimental Setup EBID Clamping AFM cantilever

  24. Tensile Testing Assuming a diameter of 1.0 nm, the corresponding Young’s modulus is 870 GPa for this specific SWCNT; with this diam strength would be ~45 GPa.

  25. TEM testing stage adapted to TEM sample holder piezodriver TEM testing stage: postdoc Henry Rohrs, 1997-99 (fabricated CNF-Hui Huang, postdoc)

  26. Why Nanorope? A B To achieve load transfer so that the full bundle cross-section would be participating in load-bearing up to the intrinsic SWCNT breaking strength, the SWCNT contact length must be on the order of 10 to 120 microns (but note that Dong gets 1.3 um for the relaxed case, 3.8 um for rigid cylinders-preliminary results) There is strong evidence, however, that the typical length of individual SWCNTs in such bundles is only about 300 nm What happens when the bundle is naturally in a twisted form or can be assembled into twisted ropes? Dong Qian, Gregory J Wagner, and Wing Kam Liu, Min-Feng Yu, Rodney S Ruoff, Mechanics of carbon nanotubes, Appl. Mech. Rev. 55, 495 (2002). Wire Rope Users Manual

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