1. Northwestern University Ruoff Group Nanotechnology 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. Northwestern University Ruoff Group Nanotechnology The group Rod RuoffRichard PinerDmitry DikinXinqi Chen NUANCE staff member Sasha Stankovich Weiqiang Ding Terry Xu UNC-Charlotte Shaoning Lu Touchdown Technologies Geoffrey Dommett, Physics Kevin Kohlhaas Robbie Cantrell PhD-MD Eric Zimney Abel Thangawng Jae Chung U Wash-Seattle Supinda Watcharatone Inhwa Jung

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

4. Northwestern University Ruoff Group Nanotechnology 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. Northwestern University Ruoff Group Nanotechnology J. Tersoff and R. S. Ruoff, Structural properties of a carbon-nanotube crystal. Phys. Rev. Lett., 73, 676-9 (1994). 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 Novel polygonized single-wall carbon nanotube bundles M J Lopez et al Phys Rev Lett 86 (14): 3056-3059 APR 2 2001 Single-walled carbon nanotube bundle comprised of SWCNTs with diameter ~ 1.4 nm. Thess et al, Science.

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 Embed in Formvar, deform at ~70 C Rod Ruoff, Rob LaDuca, Shekhar Subramoney, unpublished results

7. Northwestern University Ruoff Group Nanotechnology 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). 15-shell MWCNT

8. Northwestern University Ruoff Group Nanotechnology 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). 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.

9. Northwestern University Ruoff Group Nanotechnology Fracture Mechanics of One- Dimensional Nanostructures: outer shell of MWCNTs

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

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

15. Northwestern University Ruoff Group Nanotechnology Nanoparticle Chain Aggregates Mechanics Breaking Force: 42  25 nN Tensile Strength: 40 -100 MPa Elastic Modulus : 200 - 600 MPa Particle Contact Force: 8  4 nN Tensile Testing Stretching a chain Contact Force Measurement Carbon nanoparticle chain aggregates Nanoparticle diameter: 25-35 nm Chain length: ~ 2  m 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.

16. Northwestern University Ruoff Group Nanotechnology 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. A CNT in contact with an AFM tip, before and after EBID clamping EBID principle Hydrocarbon molecules EBID clamp Exposure area

17. Northwestern University Ruoff Group Nanotechnology MWCNT: Carbon Nanotube Source 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. 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.

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

19. Northwestern University Ruoff Group Nanotechnology MWCNT: Diameter Measurement (a) AFM chip holder model AFM cantilevers (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 Cantilever holders were designed to hold a shortened AFM chip for nanotube diameter measurement in TEM.

20. Northwestern University Ruoff Group Nanotechnology MWCNT: Stress & Strain Measurements The whole tensile testing process was recorded by taking SEM images at each loading step.

21. Northwestern University Ruoff Group Nanotechnology MWCNT: Tensile Testing Result Fracture Strength Elastic Modulus Average elastic modulus: ~ 910 GPa

22. Northwestern University Ruoff Group Nanotechnology MWCNT: Multiple Loading (Tube #6) Test # Gauge Length (  m) Breaking Force (nN) Tensile Strength (GPa) Failure Strain (%) Elastic Modulus (GPa) 14.08220 21  1.41.8  0.31200  210 23.75240 23  1.41.9  0.31250  210 33.46420 41  2.63.0  0.21230  130 (1)(2)(3)

23. Northwestern University Ruoff Group Nanotechnology SWCNT fracture mechanics… Collaboration with Jim Hone group, Columbia University Alan Cassell, NASA Ames

24. Northwestern University Ruoff Group Nanotechnology SWCNT Sample Individual or small bundle of SWCNTs spanning across a trench (from Prof. Jim Hone’s group, Columbia Univ.)

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

26. Northwestern University Ruoff Group Nanotechnology Tensile Testing Configuration Experimental Setup EBID Clamping X-Y Stage Z Stage Tipless AFM cantilever AFM cantilever

27. Northwestern University Ruoff Group Nanotechnology 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.

28. Northwestern University Ruoff Group Nanotechnology piezodriver TEM testing stage adapted to TEM sample holder TEM testing stage: postdoc Henry Rohrs, 1997-99 (fabricated CNF-Hui Huang, postdoc)

29. Northwestern University Ruoff Group Nanotechnology Why Nanorope? A A B 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