Buckytube History:
»Allotropes of Carbon
~ the fullerenes are allotropes of carbon named after the scientist and architect Richard Buckminster "Bucky" Fuller
~ discovered in 1985 by a team of scientists from Rice University and the University of Sussex
~ three were awarded the 1996 Nobel Prize in Chemistry
~ the discovery of a new molecule made purely of carbon was done with a new kind of microscope
~ buckyballs – sixty carbon atoms arranged in a soccer ball shape – had been discovered
~ are molecules composed entirely of carbon, which take the form of a hollow sphere, ellipsoid, or tube
~ spherical fullerenes are sometimes called buckyballs
~ cylindrical fullerenes are called buckytubes or nanotubes

»Buckminster Fuller
~ an American visionary, designer, architect, poet, author, and inventor
~ in the fields of design and architecture his best known invention is the geodesic dome
~ carbon molecules known as fullerenes or buckyballs were named for their resemblance to a geodesic sphere

»Geodesic Dome
~ an almost spherical structure based on a network of great circles (geodesics) lying approximately on the surface of a sphere
~ the only man-made structure that becomes proportionally stronger as it increases in size !
~ the first dome that could be called "geodesic" was designed by Walther Bauersfeld, chief engineer of the Carl Zeiss optical company
~ the dome was patented, constructed by the firm of Dykerhoff and Wydmann on the roof of the Zeiss plant in Jena, Germany
~ R. Buckminster Fuller further investigated this concept and named the dome "geodesic"
~ from field experiments with Kenneth Snelson and others at Black Mountain College in the late 1940s
~ Fuller cannot be said to be the first inventor, he exploited and developed the idea, receiving a U.S. patent
~ the geodesic dome appealed to Fuller because it was extremely strong for its weight,
~ its "omnitriangulated" surface provided an inherently stable structure, and
~ a sphere encloses the greatest volume for the least surface area
~ Fuller had hopes that the geodesic dome would help address the postwar housing crisis
~ this was in line with his prior hopes for both versions of the Dymaxion House

Buckytubes Properties:
~ a true example of nanotechnology
~ with nanometer-scale diameters and micron scale lengths they bridge the gap between nano and micro
~ are tubular fullerenes
~ polymers that are part of the fullerene family of carbon molecules discovered by Dr. Richard E. Smalley and colleagues in 1985
~ exhibit the degree of perfection associated with all molecules
~ comprise of single-wall carbon nanotubes (SWNTs), and nested (endohedral or endotopic) SWNTs
~ i.e., one, two or more tubular fullerenes nested inside another tubular fullerene
~ the special nature of carbon combines with the molecular perfection of Buckytubes
~ to endow them with exceptionally high material properties such as
~ electrical and thermal conductivity, strength, stiffness, and toughness
~ no other element in the periodic table bonds to itself in an extended network with the strength of the carbon-carbon bond
~ the delocalized pi-electron donated by each atom is free to move about the entire structure,
~ rather than stay home with its donor atom, giving rise to the first molecule with metallic-type electrical conductivity
~ the high-frequency carbon-carbon bond vibrations provide an intrinsic thermal conductivity higher than even diamond
~ in most materials the actual observed material properties - strength, electrical conductivity, etc.
~ - are degraded very substantially by the occurrence of defects in their structure
~ for example, high strength steel typically fails at about 1% of its theoretical breaking strength
~ buckytubes achieve values very close to their theoretical limits because of their perfection of structure - their molecular perfection

»Buckytubes - Understanding Their Amazing Properties
Graphene
~ the building blocks of the buckytubes
~ graphite was long considered the poor brother of diamond in the family tree but turned out to be far richer in its properties
~ a single layer of graphite is called graphene
~ in it the carbon atoms are arranged in hexagons, just like chicken-wire
~ has the distinction of being the densest known two-dimensional packing of atoms
~ no 2-D slice through diamond, or any other material, is denser on an atomic basis
~ this, together with the special nature of the carbon-carbon bonds in this network, gives graphene the highest stiffness of any sheet

Buckytube Mechanical Properties
~ take graphene and wrap it up into a tube by seamlessly connecting two opposite edges
~ you now have a tube with the greatest stiffness, both in tension and in bending
~ many materials are stiff (although not as stiff as this), but so brittle as to be often useless
~ most materials that are not brittle, such as spider silk, which can be stretched about 30% beyond its resting length, are not particularly strong
~ buckytubes, stiff as they are, are also amazingly tough
~ can stretch beyond 20% of their resting length
~ can be bent over double, and even tied into a knot and released with no resulting defect
~ this unprecedented combination of stiffness and toughness makes buckytubes by far the strongest known fibres in tension
~ – about 100 times stronger than high-strength steel at one-sixth the weight!

Thermal Conductivity
~ the tubes are also the best known conductors of heat, now verified to exceed diamond, the previous winner
~ unlike bulk diamond, however, whose thermal conductivity is the same in all directions,
~ buckytubes conduct heat far better down the tube axis than sideways from tube to tube
~ thus, a macroscopic crystal of buckytubes, where tubes are packed together,
~ all running alongside one another in the same direction, the sides with the tube ends would feel cold to the touch, like metal,
~ while the other sides would feel like wood, a good thermal insulator

Electrical Conductivity
~ where buckytubes really perform is in their electrical conductivity
~ the carbon in the planar graphene sheet is bonded in such a way as to free up one electron per carbon atom to wander around freely
~ this is what happens in metals, where some electrons are not strongly bound to their donor atom,
~ but can easily be pulled this way or that under the influence of an electric field
~ the detailed quantum mechanics of graphene results in a semimetal,
~ a situation where the in-plane conductivity is only moderate, similar to that of a poor metal like lead
~ however, when rolled into a perfect tube, something marvellous happens, again due to quantum mechanics and symmetry
~ when the graphene sheet is rolled up so that there are carbon-carbon bonds that are perpendicular to the tube axis,
~ the resulting electronic structure becomes that of a true metal, like copper or gold
~ this is the first and only instance of a molecule being a true metallic conductor
~ other ways of rolling up the graphene sheet produce semiconducting tubes
~ with such a small gap that at a few degrees above absolute zero they have high conductivity,
~ or are similar to silicon in their conductivity

Opportunities with Buckytubes
»Conductive plastics, as well as thermosets, filled with buckytubes
~ are terrific electrical conductors; no polymer is a better conductor and none better is likely to be found
~ have a phenomenally high aspect ratio
~ individual tubes are about 1 nm in diameter (about half the diameter of DNA, and about 1/10,000th the diameter of graphite fibres),
~ and 100-1000 nm in length
~ the aspect ratio of buckytubes is around 100-1000, compared with about 1 for carbon black particles
~ it pushes the critical loading level downward
~ buckytubes naturally form, in fact are born with, a morphology that is probably ideal for conductive filler applications
~ buckytubes self-assemble into “ropes” of tens to hundreds of aligned tubes, running side by side, branching and recombining
~ when examined by electron microscopy, it is exceedingly difficult to find the end of any of these ropes
~ thus, ropes form naturally occurring very long conductive pathways
~ that can be exploited in making electrically conductive filled composites
~ initial indications are that dramatically lower loadings of buckytubes are required
~ to reach a given level of conductivity than for any other conductive fillers
~ very low loadings (<0.1%) provide for antistatic and electrostatic dissipative applications

Buckytubes for Energy Storage
~ have the intrinsic characteristics desired in material used as electrodes in batteries and capacitors
~ have a tremendously high surface area (~1000 m2/g)
~ have good electrical conductivity
~ their linear geometry makes their surface highly accessible to the electrolyte
~ have the highest reversible capacity of any carbon material for use in lithium-ion batteries
~ have applications in a variety of fuel cell components
~ have a number of properties including high surface area and thermal conductivity
~ that make them useful as electrode catalyst supports in PEM fuel cells
~ are also be used in gas diffusion layers as well as current collectors because of their high electrical conductivity
~ their high strength and toughness to weight characteristics may also prove valuable as part of composite components in fuel cells
~ that are deployed in transport applications where durability is extremely important

Structural Composites
~ the world-record properties of buckytubes also include mechanical properties, such as stiffness, toughness, and strength
~ these properties lead to a wealth of applications exploiting them,
~ including advanced composites requiring high values in one or more of these properties

Painting automobile body parts
~ are increasingly made of plastics which are insulators
~ plastic parts charge up, which cause them to repel electrostatically the paint droplets formed in spray-painting of the body parts
~ this results in a great deal of wasted paint, which is both an economic and an environmental problem
~ a conductive primer coat can be applied, but that extra processing step is also quite costly
~ the ideal situation is to make the part itself sufficiently conductive to drain away charge build up
~ by connecting the part to ground during the painting process

Buckytube-filled plastics is in EMI/RFI shielding
~ has uses in portable electronics, and defence applications
~ good attenuation of electromagnetic radiation can be attained at buckytube loadings on the order of 1% or less
~ good mechanical stability should be maintained, allowing it to be moulded
~ this would represent a significant breakthrough in plastics and enable broadening of their uses
~ invisibility: radar-absorbing or modifying material for aircraft and missiles

Links
»Understanding Of Actuator Properties Of Carbon Nanotubes Bring Micro Machines Closer
»A to Z Nanotechnology
»The Fraunhofer Technology Development Group