Slowly
but surely we are getting there. Now imagine two layers on either
side of flexible stretchy material. Modest annealing might produce
almost perfect sheets of graphene. Sooner or later this is going to
be possible and here we the many ways forward.
Again
we are coming closer to the multilayered sandwich.
This
technology is now almost a decade old and the advances have been
excellent. There is little doubt that it will become central to all
aspects of technology.
Scientists create
"spray-on graphene"
May
29, 2014
Despite its many
desirable qualities and potential
applications, graphene still isn't as
widely used as it could be for one main reason – it's difficult to
apply to surfaces, particularly large ones. Attempting to do so often
causes damage to the graphene, or otherwise results in a non-uniform,
flawed coating. Now, however, scientists have devised a
method of simply spraying the stuff on, that actually improves the
graphene in the process.
Prof. Sam S. Yoon at
Korea University had already been working on a kinetic spray
deposition system, that could apply liquids to a variety of materials
by accelerating droplets to supersonic speeds via a de
Laval nozzle. He was approached by the
University of Illinois at Chicago's Prof. Alexander Yarin, who
believed that the technology could be used for the application of
graphene flakes suspended in a carrier liquid.
The result of their
collaboration is a system that reportedly applies graphene to various
substrates in a smooth, even layer. The liquid evaporates quickly,
leaving behind a coating of well-distributed flakes that resist
clumping together, but that also don't have any large empty spaces
between them.
While the relatively
flawless overall coating was what the scientists had been hoping for,
they were surprised to discover that the deposition process also
corrected flaws already present in the individual flakes. This
was likely due to the fact that the "imperfect" graphene
was forced to stretch out in all directions as it hit the substrate
at supersonic speed, its linked carbon atoms subsequently defaulting
back to a more uniform, hexagonal alignment with one another.
According to Yarin,
the new process is "simple, inexpensive, and can be
performed on any substrate with no need for post-treatment."
A paper on the
research was recently published in the journal Advanced
Functional Materials. Scientists at MIT
and the University of Michigan are developing another graphene
deposition technique, that involves the application and subsequent
removal of metal
foil to the substrate.
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