Posted on 07/28/2007 12:47:54 AM PDT by neverdem
Presto chango!
Dumping graphene oxide particles in water (top) causes them to begin binding together spontaneously into superstrong sheets.
Credit: Rod Ruoff
Researchers have developed a remarkably simple way to convert ordinary graphite particles into very thin but superstrong sheets that are tougher than steel and as flexible as carbon fiber but can be made much more cheaply. The discovery could spawn entirely new types of materials for applications as diverse as protective coatings, electronic components, batteries, and fuel cells.
For tensile strength and stiffness, carbon is king. So it's no surprise that scientists have been working for years to develop ways to add Element 6 to composite materials for aircraft fuselages, military vehicles, and even racing bicycles and tennis rackets. Even bigger payoffs are possible by constructing carbon materials at microscopic scales, yielding the strongest materials of all. Researchers have made some progress building structures called carbon nanotubes--whose single-layer atomic structure is tightly bound and therefore super rigid--but the tubes are expensive to manufacture and so far can only be used in tiny amounts.
Now, a research team from Northwestern University in Evanston, Illinois, has assembled particles of graphene oxide, a form of graphite and a cousin of diamonds, into very thin sheets that are even stronger than those made of the nanotubes. The process works like this: the team disperses graphene oxide particles in specially treated water and then draws the mixture through a filter membrane. The water somehow causes the particles to bind into a paperlike layer on the filter's surface, the researcher reports in tomorrow's Nature. "We actually don't know all of the details of how the layering takes place," says physical chemist and co-author Rod Ruoff. Laboratory tests showed that the grapheme paper was as strong as that made from carbon nanotubes, yet unlike nanotubes, the material can be fabricated to any size. That makes graphene paper a prime candidate for a new generation of superstrong composite materials, Ruoff says.
The super paper does have its kryptonite, however. The sheets remain stable when exposed to air, says Ruoff, but immersing them in water slowly loosens the bonds. Also, says materials scientist Boris Yakobson of Rice University in Houston, Texas, because water is so common as either liquid as rain or vapor as humidity, it will likely affect graphene sheets exposed to the environment in the long run if the material can't be protected from water's effects. So, the next task is to find other molecules that can replace water in the fabrication process. That research challenge and others probably puts commercialization of the technology at least 5 or 10 years away, Ruoff says.
Or by someone just walking the dog.....
Leni
Wow! That's the first thing that I thought of. This graphene "super paper" could be used for the portion of the elevator outside the atmosphere, with carbon nanotube-based ribbon being used for the portion inside the earth's atmosphere (where it would encounter moisture). Either that, or use it the whole way with a layer of protection for the portion inside the atmosphere.
A manufacturing process could probably be developed which would allow this to be produced in continuous sheets.
OR. Equally promising might be to find a substance (or make an artificial one) that would, by its makeup like to bond with graphene. Then a second step in the process could include putting finished sheets through a process - like the "layering" processes used in semi-conductors - that places a coating impervious to water on the the finished sheets. The sheets would still have all the strength and flexibility as before, while - with the exception of major physical damage - not degrade in the presence of moisture. There are many applications - building construction - where such sheets could be very useful and stable. Yes, flying debris from storms, fire or explosions can damage a structure, but when they do the damaged elements of the structure need to be replaced anyway, so it would be no different for properly coated graphene sheets.
Fantastic! Oh, wait, it can’t be exposed to water or it dissolves....No sneezing on graphene oxide spaceships then.
Gee, the first thing I thought of was light weight body armor. I need to go eat some breakfast....
Oh yeah! We would have to reverse the polarity on the emitter array, but it just might work!
Scientists slice graphite into atom-thick sheets
The Register (U.K.) | October 21, 2004 | Lucy Sherriff
Posted on 10/22/2004 3:09:03 AM EDT by Stoat
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