Carbon nanotubes are fullerene-related structures consisting of graphene cylinders closed at either end with pentagonal rings. There are two main types: single-walled nanotubes (SWNTs), which have diameters around 1 nanometer, and multi-walled nanotubes (MWNTs) made of multiple concentric graphene cylinders. Functionalization of carbon nanotubes is important for applications and can occur through non-covalent interactions like wrapping of surfactants or polymers or through covalent bonding by attaching molecules to existing defects or through reactions to functionalize the graphene sidewalls. The document discusses different methods of non-covalent and covalent functionalization of carbon nanotubes.

1. CARBON NANOTUBES-
TREATMENT AND
FUNCTIONALIZATION
BY,
LINI CLEETUS C
2ND
M.Sc BPS
CBPST, KOCHI

2. Example Bullet Point Slide
Carbon nanotubes are fullerene-related
structures which consist of graphene
cylinders closed at either end with caps
containing pentagonal rings
CARBON NANOTUBES

3. SINGLE WALLED NANO TUBES
 Most single-walled nanotubes (SWNT) have a diameter of
close to 1 nanometer, with a tube length that can be
many millions of times longer
 The structure of a SWNT can be conceptualized by
wrapping a one-atom-thick layer of graphite called
graphene into a seamless cylinder
 The way the graphene sheet is wrapped is represented by
a pair of indices (n,m) called the chiral vector
 The integers n and m denote the number of unit vectors
along two directions in the honeycomb crystal lattice of
graphene
 If m = 0, the nanotubes are called "zigzag". If n = m,
the nanotubes are called "armchair". Otherwise, they are
called "chiral"
Zigzag (n,0)
Chiral (n,m)

4. MULTI WALLED NANOTUBES
Multi-walled nanotubes (MWNT) consist of multiple
rolled layers (concentric tubes) of graphite
In the Russian Doll, sheets of graphite are
arranged in concentric cylinders
In the Parchment model, a single sheet of graphite
is rolled in around itself, resembling a scroll of
parchment or a rolled newspaper

5. TREATMENT AND
FUNCTIONALIZATION
 CNTs unique properties make them desirable for many different applications.
However, to exploit as much as possible these properties, most of the
applications require the functionalization of carbon nanotubes, such as
changing the surface properties to make nanotubes soluble in different
media, or attaching functional groups or polymer chains for specific
utilizations of modified nanotubes

6. TYPES OF
FUNCTIONALIZATION
Endohedral functionalization
Exohedral functionalization

7. Example Bullet Point SlideEndohedral functionalization; CNTs are
treated by filling their inner empty cavity with different
molecules or nano particles
Schematic representation of a SWNT filled with C60 fullerenes

8. Example Bullet Point Slide
Exohedral functionalization;
It involves grafting of molecules on the outer surface of
nanotubes
Several approaches have been developed and include defect
functionalization covalent functionalization and noncovalent
functionalization with surfactants or polymers
The different types of exohedral functionalization can be
classified via the nature of the interactions between the
surface of carbon nanotubes and the functional groups or
polymer chains
These interactions can rely upon covalent or non-
covalent bonds.

9. Example Bullet Point Slide
• Bullet point
– Sub Bullet
Functionalization possibilities for CNTs: defect functionalization
(A),
covalent sidewall functionalization (B), noncovalent
functionalization with surfactants (C) and polymer wrapping (D)

10. NON-COvALENT
FUNCTIONALIZATION wITh
SUrFACTANT Or POLYmEr
The noncovalent interaction is based on van der Waals forces
or - stacking and it is controlled by thermodynamicsπ π
The great advantage of this type of functionalization relies
upon the possibility of attaching various groups without
disturbing the electronic system of the rolled grapheneπ
sheets of CNTs
The formation of non-covalent aggregates with surfactants is a
suitable method for dispersing individual nanotubes in aqueous
or organic solvents

11. Example Bullet Point Slide
• Bullet point
– Sub Bullet
Interaction of nanotubes with pyrene derivatives

12. Carbon nanotubes can be also wrapped with polymer chains to form supramolecular
complexes of CNTs
Different steps in PE coating of nanotubes is given below

13. Covalent funCtionalization
Two major groups of chemical functionalization of CNTs via
covalent attachment can be distinguished, the end and
“defect-group” chemistry and the sidewall functionalization
 end and defeCt-side Chemistry
 The functionalization via “end and defect-side” chemistry
consists to graft functional group directly on the already
existing defects in the structure of CNTs
 Indeed, carbon nanotubes are generally described as perfect
graphite sheets rolled into nanocylinders.
 In reality, all CNTs present defects and can be curved

14. Typical defects in a SWNT
This method was used to graft amine
moieties onto carbon nanotubes via the reaction
with diamines such as triethylenetetramine,
ethylenediamine or 1,6-hexamethylenediamine
The figure shows open end of the SWNT
terminated with –COOH groups. Other
terminal groups, such as –OH, -H and =O, are also
possible

15.  sidewall funCtionalization
It involves grafting of chemical groups through reactions onto
the -conjugated skeleton of CNTsπ
The reactivity of CNT sidewalls remains low and sidewall-
functionalization is only successful if a highly reactive reagent
is used, whereas the nanotube caps are quite reactive due to
their fullerene-like structure
Another constraint for sidewall functionalization is the tendency
of CNTs to form
bundles and to limit the available nanotube surface for the
grafting of chemical reagents
A large majority of covalent sidewall functionalizations is
carried out in organic solvent, which allows the utilization of
sonication process to improve the dispersion of CNTs and, thus,
the available surface of carbon nanotubes

16. Schematic describing various common covalent sidewall functionalization reactions of CNTs
using organic solvents

17. Example Bullet Point Slide
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