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Atom-thick carbon sheets set new strength record - acrylic glass

by:Cailong     2019-08-11
Atom-thick carbon sheets set new strength record  -  acrylic glass
Carbon supermaterials graphene is known for its unique electronic properties.
Two studies have now shown that this material is also one of the strongest, most elastic, and most rigid materials known scientifically.
Graphene crystals are atoms
The carbon atoms of the thick sheet are connected together in a hexagon, just like the chicken wire.
Whenever we put the pencil on paper, a sheet of graphene is generated-the graphite in the pencil is just a 3D structure containing multi-layer graphene.
However, graphene was separated for the first time in 2004.
Since then, in the "gold rush" of graphene, scientists have scrambled to discover the properties of the material and discover potential applications.
Large surfaceto-
The volume ratio and high conductivity have been suggested in the Super
Small electronic products
Now, researchers have found that graphene also has significant mechanical properties.
Long Valley Lee and Xiao Ding Wei of Columbia University in New York put a graphene sheet with a diameter of 10 to 20 microns on a silicon wafer with only 1 to 1 hole.
5 microns in diameter, like a micro muffin plate.
The graphene above the small hole was not supported, and Lee and Wei poked at the Diamond Tip of the atomic force microscope to see how easily graphene was deformed and cracked.
They found that graphene can push down 100 nanometers with a force of up to 2.
Nine needles before the rupture
The researchers estimated that the fracture strength of graphene was 55 newton per meter.
"As a way to imagine the force required to break the film, imagine trying to pierce a graphene that is as thick as a normal plastic food package-usually 100 microns in thickness," James haehom said, he is the head of the Columbia lab where Li studied.
"It will take more than 20,000 Newton's force, equivalent to the weight of 2000 kg cars.
This strength, Hone says, actually leaves graphene off the charts of the strongest materials.
"These measurements constitute a strength benchmark that can never be achieved by a macro system, but can hopefully be approached," he said . ".
In separate work, Tim Booth and Peter Black of the University of Manchester, UK are introducing atomic perfect graphene into the macro world from a nano-microscope.
Their team got a patent for a new method of free production
Upright graphene sheet with a diameter of up to 100 microns.
The researchers used tape to remove tiny graphene sheets from graphite, and as their technology improved, they began to produce larger and larger sheets.
The flakes can be removed from the tape manually, or the tape can be dissolved with acetone.
One problem with this approach is that adhesive tape picks up multiple flakes
Layered graphite at the same time.
Finding graphene is like a needle in a haystack.
The key is to put all the flakes on the silicon wafer, and the properties of graphene make it easy to find under an optical microscope.
However, graphene flakes combine with silicon and are easily damaged when scientists try to remove them.
One solution is to consume Silicon and release graphene using corrosive chemicals such as hf, but this tends to chemically pollute graphene and change its performance.
Now Booth and Blake realize that acrylic glass (PMMA)
With the same optical properties as silica, graphene sheets can also be highlighted.
However, it is easily dissolved in acetone, a less active chemical that does not change graphene.
Booth and Blake can easily separate large crystals using their technology. ‘Science-
The novel application, Booth said, "We are limited only by the size of the sheet of graphene available . ".
"There is no reason why this method will not extend to larger flakes.
Booth and Blake also found that graphene is very hard using these flakes.
Crystals supported only on one side extend nearly 10 microns without any support-equivalent to an unsupported piece of paper with a length of 100.
It was previously assumed that graphene would curl up if not supported.
Intuitively, Booth said, the team has shown that this should actually be expected from the theoretical measurement of the stiffness of the material.
Graphene can be added to the polymer to form a super
The strength of the composite, Booth said.
"However, the unique combination of graphene properties and colon may be the most interesting application;
"Transparency, electronic structure, stiffness, thermal conductivity," he said . ".
"This may help to achieve science --
Novel application.
Journal references and colons; Science (DOI: 10. 1126/science. 1157996);
Nano Letters (DOI: 10. 1021/nl801412y)
Nanotechnology-in our constantly updated special report, with the advent of new technologies.
In our constantly updated feature report
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