Alice’s Adventures in “Nanotube”land! Nikta Fakhri Chemical and Biomolecular Engineering Department Illustration by Sir John Tenniel from Lewis Carroll's Alice's Adventures in Wonderland.
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Alice’s Adventures in “Nanotube”land! Nikta Fakhri Chemical and Biomolecular Engineering Department Illustration by Sir John Tenniel from Lewis Carroll's Alice's Adventures in Wonderland (1865) OUTLINE What is a carbon nanotube (CNT)? What is a single-walled carbon nanotube (SWNT)? How to Produce SWNT? Why do we care (SWNT properties)? Potential application Dispersing SWNTs IT ALL STARTS WITH CARBON SINGLE-WALLED vs. MULTI-WALLED CNTs ~ 0.7 – 5 nm diameter Better properties ~ 3 – 100 nm diameter Wider availability Length: on the order of microns L / D ~ 1000 SWNT: ROLLED-UP SHEET OF GRAPHITE SOME GEOMETRY! a1 1 1 6 2 6 2 3 5 3 a2 5 4 4 1 6 2 5 3 4 WHAT IS CHIRALITY? Properties of nanotubes are determined by chirality Chiral numbers are noted by (n,m) n counts in the direction of a1 and m counts in the direction of a2 WHAT IS CHIRALITY? NOT ALL SWNTs ARE CREATED EQUAL n-m divisible by 3: metallic otherwise: semiconducting Bachilo et al 2002 O’Connell et al 2002 PRODUCING NANOTUBES CNT, C60 PRODUCING NANOTUBES High-Pressure Carbon Monoxide Deposition: HIPCO CO + CO C(s) + CO2 Fe Mixture of length and chirality PRODUCING NANOTUBES SWNT PROPERTIES Exceptional mechanical strength Tensile strength > 37 GPa (Steel 2 Gpa) Young modulus ~ 0.62 – 1.25 TPa (Steel 0.3 Tpa) Low density ~ 1.4 g/cm3 (Steel ~8 g/cm3, Aluminum 2.7 g/cm3) Electrical resistivity ~ 1 mW cm (Copper 1.7 mW cm) Thermal conductivity ~ 3000 W / m K (Diamond ~ 2000 W / m K) Review by Baughman et al., Science, 297, 787 (2002) SOME POTENTIAL APPLICATIONS High-performance, lightweight fibers Replace Kevlar (PPTA) & Zylon (PBO) High thermal conductivity fibers Heat pipes for space applications “Ballistic” electrical conductors The Armchair Quantum Wire Nearly lossless power transmission over > 1000 km No cooling (unlike High Temp Superconductors) Conductive transparent sheets & coatings Multifunctional fibers and materials The ultimate carbon material !!! SWNT ROADBLOCKS Biggest problems 1993 (discovery)-onward “No” availability of high-quality SWNTs (until 1995) Very low availability of SWNTs (until ~ 1998) Biggest problem 1998-onward How to assemble / process SWNTs into macroscopic objects (fibers, sheets, etc.) PROCESSING In order to make fibers and sheets of CNTs we have to process them in liquid phase PUTTING CARBON NANOTUBES TO USE MAKING FILMS AND FIBERS Liquid processing Carbon nanotubes are sticky! (direct result of van der Waals forces Dispersion of nanotubes is important if you want to work with them Possible approaches ? 1. Wrapping the nanotube 2. Functionalization 3. Acids 1. WRAPPING THE NANOTUBES Put the nanotubes in the “wrapper” solution PHYSICAL Bombard them with sound waves to break the bundles (sonication) Drawbacks ??? Application: making films, biomedicine Islam et al. Nano Letters 3, 269-273 (2003) 2. SIDE-WALL FUNCTIONALIZATION Covalently bond “functional” groups to the side walls Open the carbon bonds Attach a molecule to the open bond to perform a desired “function”: disperse better! Drawbacks ??? Application: biomedicine CHEMICAL www.sunysb.edu/chemistry/ faculty/swong.htm 3. ACID Application: making fibers Acid protonates the side walls of carbon nanotubes A dense layer of sulfuric acid anions surrounds the individual nanotubes Drawbacks ??? Which method is better? Depends on application Ericson et al., Science 2004: Vol. 305. no. 5689, pp. 1447 - 1450 IMPORTANT POINTS Carbon nanotubes are a class of materials Two main subclasses: Multi-walled Single-walled Each subclass is not a chemical species Chirality (n,m) identifies the species Now (2008): Mixtures of chiralities Mixtures of lengths CONCLUSIONS Carbon nanotube has some work to do!! MWNTs when cost is important (bulk) SWNT for high-value applications Manufacturing is maturing Dispersion & liquid processing “under control” Tailored to host material Tailored to applications CONCLUSIONS “Nanotubeland” plays by its own rules: rules we have yet to understand fully! Illustration by Sir John Tenniel from Lewis Carroll's Alice's Adventures in Wonderland (1865) WE ARE ALMOST THERE: NANO-RACQUETS Babolat Racquet: Reinforced in the throat and the bottom half of the head with carbon nanotubes Net result: increase in stiffness and power of the racquet without adding weight Price: $199 SWNT MODEL “TO SCALE” World’s largest SWNT model (22 April 2005, Guinness world record) Model of a (5,5) SWNT ~65,000 pieces 360 m long, 0.36 m wide about 80 builders over 1000 in attendance SMALL is really BIG!! PROFESSOR SMALLEY PROFESSOR PASQUALI Be a scientist, save the world!