Highly Concentrated Aqueous Dispersions of Carbon Nanotubes for Flexible and Conductive Fibers

Transcription

1 Highly Concentrated Aqueous Dispersions of Carbon Nanotubes for Flexible and Conductive Fibers Laurent Maillaud 1, Robert J. Headrick 1, Vida Jamali 1, Julien Maillaud 1, Dmitri E. Tsentalovich 1, Wilfrid Neri 2, E. Amram Bengio 1, Francesca Mirri 1, Olga Kleinerman 3, Yeshayahu Talmon 3, Philippe Poulin 2, Matteo Pasquali 1 * 1 Department of Chemical and Biomolecular Engineering, Department of Chemistry, Department of Materials Science & NanoEngineering, The Smalley-Curl Institute, Rice University, Houston, Texas, 77005, United States 2 Centre de Recherche Paul Pascal - CNRS, 115 Avenue du Dr. Schweitzer, Pessac, France. 3 Department of Chemical Engineering and the Russell Berrie Nanotechnology Institute (RBNI), Technion-Israel Institute of Technology, Haifa , Israel * corresponding author: mp@rice.edu 1

2 Supporting information Raman spectroscopy data on oleum-treated SWCNTs Figure S1. Raman spectrum taken with a 633 nm excitation wavelength for as received SWCNTs (yellow), and oleum-treated SWCNTs before (red) and after (green) sonication. Cross-sectional surface area measurement of SWCNT fibers SWCNT fiber cross-sections were measured after mechanical tensile tests using a light microscope (Leica DM 2500 P) in reflected mode and using Leica Application Suite software for analysis. Cross-sectional surface areas of each mechanically tested fiber were measured on five different points along the fiber. Figure S2 shows the difference in the diameter before and after washing due to the surfactant removal. 2

3 Figure S2. Light microscopy images of 1.8 wt.% fiber cross-sections before (a) and after (b) water washing. Cross section area on image (a) is µm 2 and cross section area on image (b) is µm 2. Insets show analyzed images using the microscope software to determine fiber cross section areas. Cryo-TEM specimen preparation of SWCNT aqueous dispersions A small drop (ca. 3 µl) of sample dispersion was applied on a perforated carbon film supported on a copper TEM grid, held by tweezers inside a controlled environment vitrification system (CEVS) 1. To achieve good wettability of the support, the perforated films were treated with glow discharge air-plasma (PELCO easiglowtm, Ted Pella Inc., Redding, CA, U.S.A). The CEVS chamber was kept at 25 C and saturated with a main component of our system: water/doc (1 wt. %) solution. The drop was thinned into a film, less than 300 nm thick, by blotting away excess solution with a filter paper wrapped over a metal strip. The specimen was then plunged into liquid ethane at its freezing point to achieve fast cooling rate. The specimens were examined in a Philips CM120 transmission electron microscope at an accelerating voltage of 120 kv. We used a Gatan 626 cryo-holder to maintain the vitrified specimens below 175 C. Specimens were studied in the low-dose imaging mode to minimize electron-beam radiation-damage. Images were recorded digitally by a Gatan MultiScan 791 cooled CCD camera, using the DigitalMicrograph software (Gatan, UK). 3

4 Figure S3. Cryo-TEM micrographs of CNT/DOC/water dispersions at (a-b) 0.05 wt.% of CNTs, 1 wt.% of DOC. This concentration is used to estimate SWCNT average length by bootstrap analysis. (c-d) 0.3 wt.% of CNTs, 1 wt.% of DOC, showing both isotropic (c) and liquid crystalline (d) phases. Ordered domains are several microns in length. Black dots are ice crystals. 4

5 Figure S4. Bootstrapped length estimate and standard error (inset) as a function of bootstrapped set size b for SWCNT CG301X after 20 min of sonication at 15 Watts. 5

6 Figure S5. Movie of a SWCNT fiber continuously spun, through a spinneret immersed in a coagulation bath (acetone), from a 1.8 wt.% SWCNT aqueous dispersion. After coagulation, the fiber is collected around a drum. The draw ratio was

7 Figure S6. SEM images of a 0.3 wt.% fiber showing inhomogeneous shape and diameter. 7

8 1.0 wt.% fibers Stress (MPa) raw washed Strain (%) 1.8 wt.% fibers 1000 Stress (MPa) raw 200 washed Strain (%) Figure S7. Multiple tensile break tests on SWCNT fibers made from aqueous dispersions concentrated at 1.0 wt.% (a) and 1.8 wt.% (b) in SWCNT. Consistent results show that the fiber mechanical properties change by increasing SWCNT concentration and by washing the fibers with water. 8

9 Figure S8. Multiple tensile break tests on washed SWCNT fibers made from aqueous dispersions concentrated at 1.8 wt.% before (red) and after (black) iodine doping, showing that the fiber mechanical properties remained the same after iodine doping. 9

10 Figure S9. Mechanical properties of the fibers reported in this work in comparison with the reported values in the literature for fibers made from aqueous dispersions. References (1) Bellare, J. R.; Davis, H. T.; Scriven, L. E.; Talmon, Y. Controlled Environment Vitrification System: An Improved Sample Preparation Technique. J. Electron Microsc. Tech. 1988, 10 (1),