Chemical Technology March 2015

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FOCUS ON CORROSION& COATINGS
A new process for coating copper nanowires
with graphene - an ultrathin layer of carbon
– lowers resistance and heating, suggesting
potential applications in computer chips and
flexible displays.
“Highly conductive copper nanowires
are essential for efficient data transfer and
heat conduction in many applications like
high-performance semiconductor chips and
transparent displays,” said doctoral student
Ruchit Mehta, working with Zhihong Chen, an
associateprofessor of electrical and computer
engineering at Purdue University.
Now, researchers have developed a tech-
nique for encapsulating the wires with gra-
phene and have shown that the hybrid wires
are capable of 15 % faster data transmission
while lowering peak temperature by 27 %
compared with uncoated copper nanowires.
“This is compelling evidence for improved
speed and thermal management by adapt-
ing the copper-graphene hybrid technology
in future silicon chips and flexible electronic
applications,” he said.
Researchers and industry are trying to
create smaller wires to increase the ‘packing
density’ of electronic components in chips.
However, while smaller wires are needed to
increase performance and capacity, scaling
down the size of the wires reduces electrical
and thermal conductivity, which can lead to
overheating and damage. The graphene coat-
ing prevents the copper wires from oxidising,
preserving low resistance and reducing the
amount of heating. “If the surface is covered
with oxide then a lot of the electrical and ther-
mal conductive properties of copper are lost,”
Mehta said. “This is very important because
you want as much current as possible going
through these wires to increase speed, but
they cannot take too much current because
they will melt. But if the copper has good
electrical and thermal conductivity you can
push more current through it.”
Thehybridwires arepromising for transpar-
ent and flexible displays because they could
be used in sparse numbers, maintaining
transparency, and they arebendable. “Copper
wires usually aren’t good for these displays
because they eventually oxidize and stop
working,” Mehta said. “If you can prevent the
oxidation, they potentially become a good fit.”
Until now it has been difficult to coat cop-
per nanowires with graphene because the
process requires chemical vapour deposition
at temperatures of about 1 000 ºC, which
degrades copper thin films and small-dimen-
sionwires. The researchers have developed a
new process that can be performed at about
650 ºC, preserving the small wires intact,
using a procedure called plasma-enhanced
chemical vapour deposition. Wires were
tested in twowidth sizes: 180nanometres - or
more than 500 times thinner than a human
hair - and 280 nanometres.
Story by Emil Venere, 765-494-4709,
z
Hybrid nanowires eyed for computers, flexible displays
This graphic depicts
a copper nanowire
coated with graphene
- an ultrathin layer
of carbon (Purdue
University)
Leading global specialty chemicals group
Perstorp will unveil new products and en-
hanced support at the European Coatings
Show 2015 as part of its on-going com-
mitment to strengthen its offering for the
global coatings and resins market.
Perstorp’s raw materials enable custom-
ers to create coatings systems with high perfor-
mance and low environmental impact, for a wide
range of decorative and industrial applications
used in emerging growth markets such as coatings
for electronic parts and materials, printing inks and
pre-coating wood.
Products making their European Coatings Show
debut will include: a new addition to the Capa™
portfolio –Capa™ Lactide 8000 series, partially re-
newable polyols for 2 K and 1 K industrial coatings.
These new transparent liquid polyols are particularly
suitable for production of high performance soft-
touch coatings as well as coatings with enhanced
adhesion to various substrates, and which require
no solvents.
The latest extension toPerstorp’sOxymer™range
of polycarbonatediols for increasedweatherability of
polyurethane dispersions (PUDs) aswell as castable
and thermoplastic elastomers will be seen. New
Oxymer™ HD types Oxymer™ HD56 and Oxymer™
HD112 are based on 1,6-hexane diol.
Charmor™ PM40 Care, which provides the next
development step in safe carbon sourceproducts for
intumescent systems is another newcomer. It has an
“unmatchable environmental profile”, being based
on renewable feedstocks. Charmor is a leading car-
bon source for intumescent coatings that preserve
the integrity of steel structures when temperatures
reach around 500 °C in a fire.
Perstorp has also invested in new capacity for
its Neopentyl Glycol essential building blocks for
powder coatings and stoving enamels, demonstrat-
ing its long-standing commitment to the Chinese
coatings market.
For more information tel +46 435 380 00 or email
z
Perstorp to launch new
high-performance products
at ECS 2015