Buckypaper
Encyclopedia
Personal armor
Personal armor is the whole of protecting clothing, designed to absorb and/or deflect slashing, bludgeoning, and penetrating attacks. They were historically used to protect soldiers, whereas today, they are also used to protect police forces, private citizens and private security guards or...
and next-generation electronics
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
and displays.
Background
Buckypaper is a macroscopic aggregate of carbon nanotubes (CNT), or "buckytubes". It owes its name to the buckminsterfullereneBuckminsterfullerene
Buckminsterfullerene is a spherical fullerene molecule with the formula . It was first intentionally prepared in 1985 by Harold Kroto, James Heath, Sean O'Brien, Robert Curl and Richard Smalley at Rice University...
, the 60 carbon fullerene
Fullerene
A fullerene is any molecule composed entirely of carbon, in the form of a hollow sphere, ellipsoid, or tube. Spherical fullerenes are also called buckyballs, and they resemble the balls used in association football. Cylindrical ones are called carbon nanotubes or buckytubes...
(an allotrope of carbon with similar bonding that is sometimes referred to as a "Buckyball" in honor of R. Buckminster Fuller).
Synthesis
The generally accepted methods of making CNT films involves the use of non-ionic surfactantSurfactant
Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...
s, such as Triton X-100 and sodium lauryl sulfate, which improves their dispersibility in aqueous solution. These suspensions can then be membrane filtered under positive or negative pressure to yield uniform films. The Van der Waals force
Van der Waals force
In physical chemistry, the van der Waals force , named after Dutch scientist Johannes Diderik van der Waals, is the sum of the attractive or repulsive forces between molecules other than those due to covalent bonds or to the electrostatic interaction of ions with one another or with neutral...
's interaction between the nanotube surface and the surfactant can often be mechanically strong and quite stable and therefore there are no assurances that all the surfactant is removed from the CNT film after formation. Washing with methanol, an effective solvent in the removal of Triton X, was found to cause cracking and deformation of the film. It has also been found that Triton X can lead to cell lysis and in turn tissue inflammatory responses even at low concentrations.
In order to avoid adverse side-effects from the possible presence of surfactants, an alternative casting process can be used involving a frit compression
Frit compression
Frit compression is the technique used to fabricate buckypaper and buckydiscs from a suspension of carbon nanotubes in a solvent. This is a quick, efficient method over surfactant-casting or acid oxidation filtration of carbon nanotubes.-Background:...
method that did not require the use of surfactants or surface modification. The dimensions can be controlled through the size of the syringe housing and through the mass of carbon nanotubes added. Their thicknesses are typically much larger than surfactant-cast buckypaper and have been synthesized from 120 μm up to 650 μm; whilst no nomenclature system exists to govern thicknesses for samples to be classified as paper, samples with thicknesses greater than 500 μm are referred to as buckydiscs. The frit compression method allows rapid casting of buckypaper and buckydiscs with recovery of the casting solvent and control over the 2D and 3D geometry.
Aligned multi-walled carbon nanotube (MWCNT) growth has been used in CNT film synthesis through the domino effect
Domino effect
The domino effect is a chain reaction that occurs when a small change causes a similar change nearby, which then will cause another similar change, and so on in linear sequence. The term is best known as a mechanical effect, and is used as an analogy to a falling row of dominoes...
. In this process, "forests" of MWCNTs are pushed flat in a single direction, compressing their vertical orientation into the horizontal plane, which results in the formation of high-purity buckypaper with no further purification or treatment required. By comparison, when a buckypaper sample was formed from the 1 ton compression of chemical vapor deposition (CVD) generated MWCNT powder, any application of a solvent led to the immediate swelling of the film till it reverted into particulate matter. It appears that for the CNT powder used, compression alone was insufficient to generate robust buckypaper and highlights that the aligned growth methodology generates in-situ tube-tube interactions not found in CVD CNT powder and are preserved through to the domino pushing formation of buckypaper.
Properties
Buckypaper is one tenth the weight yet potentially 500 times stronger than steel when its sheets are stacked to form a composite. It could disperse heat like brass or steel and it could conduct electricity like copper or silicon. Rice UniversityRice University
William Marsh Rice University, commonly referred to as Rice University or Rice, is a private research university located on a heavily wooded campus in Houston, Texas, United States...
scientist Wade Adams says, "All those things are what a lot of people in nanotechnology have been working toward as sort of Holy Grail
Holy Grail
The Holy Grail is a sacred object figuring in literature and certain Christian traditions, most often identified with the dish, plate, or cup used by Jesus at the Last Supper and said to possess miraculous powers...
s."
Applications
Among the possible uses for buckypaper that are being researched:- Fire protection: covering material with a thin layer of buckypaper significantly improves its fire resistance due to the efficient reflection of heat by the dense, compact layer of carbon nanotubes or carbon fibers.
- If exposed to an electric chargeElectric chargeElectric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter. Electric charge comes in two types, called positive and negative. Two positively charged substances, or objects, experience a mutual repulsive force, as do two...
, buckypaper could be used to illuminate computer and television screens. It could be more energy-efficient, lighter, and could allow for a more uniform level of brightness than current cathode ray tubeCathode ray tubeThe cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and...
(CRT) and liquid crystal displayLiquid crystal displayA liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly....
(LCD) technology. - Since individual carbon nanotubes are one of the most thermally conductiveThermal conductivityIn physics, thermal conductivity, k, is the property of a material's ability to conduct heat. It appears primarily in Fourier's Law for heat conduction....
materials known, buckypaper lends itself to the development of heat sinks that would allow computers and other electronic equipment to disperse heat more efficiently than is currently possible. This, in turn, could lead to even greater advances in electronic miniaturization. - Films also could protect electronic circuits and devices within airplanes from electromagneticElectromagnetismElectromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...
interference, which can damage equipment and alter settings. Similarly, such films could allow military aircraft to shield their electromagnetic "signatures", which can be detected via radar. - Buckypaper could act as a filter membrane to trap microparticles in air or fluid. Because the nanotubes in buckypaper are insoluble and can be functionalized with a variety of functional groups, they can selectively remove compounds or can act as a sensor.
- Produced in high enough quantities and at an economically viable price, buckypaper composites could serve as an effective armor plating.
- Buckypaper can be used to grow biological tissue, such as nerve cells. Buckypaper can be electrified or functionalized to encourage growth of specific types of cells.
- The Poisson's ratioPoisson's ratioPoisson's ratio , named after Siméon Poisson, is the ratio, when a sample object is stretched, of the contraction or transverse strain , to the extension or axial strain ....
for carbon nanotube buckypaper can be controlled and has exhibited auxeticAuxeticsAuxetics are materials that have a negative Poisson's ratio. When stretched, they become thicker perpendicular to the applied force. This occurs due to their hinge-like structures, which flex when stretched...
behavior, capable of use as artificial muscles.
See also
- Frit compressionFrit compressionFrit compression is the technique used to fabricate buckypaper and buckydiscs from a suspension of carbon nanotubes in a solvent. This is a quick, efficient method over surfactant-casting or acid oxidation filtration of carbon nanotubes.-Background:...
- Carbon nanotubeCarbon nanotubeCarbon nanotubes are allotropes of carbon with a cylindrical nanostructure. Nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1, significantly larger than for any other material...
- Graphene oxide paperGraphene Oxide PaperGraphene oxide paper or graphite oxide paper is a composite material fabricated from graphite oxide.The material has exceptional stiffness and strength, due to the intrinsic strength of the two-dimensional graphene backbone and to its interwoven layer structure which distributes loads.The starting...
- Potential applications of carbon nanotubesPotential applications of carbon nanotubesCarbon nanotubes, a type of fullerene, have potential in fields such as nanotechnology, electronics, optics, materials science, and architecture. Over the years new applications have taken advantage of their unique electrical properties, extraordinary strength, and efficiency in heat...