Chemistry Reference
In-Depth Information
SWNTs are an important kind of carbon nanotube due to most of their
properties change considerably with the
(n, m)
values, and according
to
Kataura plot
, this dependence is unsteady. Mechanical properties of
single SWNTs were predicted remarkable by Quantum mechanics calcu-
lations as Young's modulus of 0.64-1 TPa, Tensile Strength of 150-180
GPa, strain to failure of 5-30% while having a relatively low density of
1.4-1.6 g/cm
3
.
These high stiffness and superior mechanical properties for SWNTs
are due to the chemical structure of the repeat unit. The repeat unit is
composed completely of sp
2
hybridized carbons and without any points
for flexibility or rotation. Also, Single walled nanotubes with diameters
of an order of a nanometer can be excellent conductors for electrical
industries.
In most cases, SWNTs are synthesized through the reaction of a gas-
eous carbon feedstock to form the nanotubes on catalyst particles.
9.3.1.2
MULTI-WALLED CARBON NANOTUBE
Multi-walled nanotubes (MWNT) consist of several concentric graphene
tubes, which its interlayer distance is around 3.4 Å; close to the distance
between graphene layers in graphite. Its single shells in MWNTs can be
explained as SWNTs.
9.3.1.3
DOUBLE-WALLED CARBON NANOTUBES (DWNT)
Double-walled carbon nanotubes consist of a particular set of nanotubes
because their morphology and properties are comparable to those of
SWNT but they have considerably superior chemical resistance. Promi-
nently, it is important when grafting of chemical functions at the surface
of the nanotubes is required to achieve new properties of the CNT. In this
processing of SWNT, some
C=C
double bonds will be broken by cova-
lent functionalization, and thus, both mechanical and electrical proper-
ties of nanotubes will be modified. About of DWNT, only the outer shell
is modified.
