This document discusses nanotechnology and nanomaterials. It defines nanomaterials as materials that have at least one dimension between 1-100 nm. It discusses different types of nanomaterials like metals, ceramics and polymers. It also defines nanotechnology as the application of scientific knowledge at the nano-scale for industrial purposes. Some common techniques used in nanotechnology like top-down and bottom-up approaches are mentioned. The document then focuses on the synthesis of nanoparticles using the sol-gel method and discusses the different steps involved in the process. Applications of nanotechnology including the use of aerogels and fullerenes are highlighted. A brief history of nanotechnology and properties of carbon nanotubes are also summarized.

1. NANOTECHNOLOGY
Dr. SWASTIKA N. DAS
PROFESSOR OF CHEMISTRY
BLDEA CET

6. NANOMATERIALS:
• Nano materials are the materials having at least one dimension,
length, width or height in the nano range. i.e. 1-100 nm. They can be
metals, ceramics, polymeric material or composite material etc.
• 1 nm = 10-9 meter
• A nanometre is one billionth of a meter, i.e. approximately 1
lac times smaller than the diameter of a human hair.
• Nanometre is used to measure things that are very small. Example:
DNA width (2nm), Hydrogen atom (0.1nm), Red blood cells (500 nm) etc…
NANO TECHNOLOGY:
• The application of science and scientific knowledge at the nano-scale. For
industrial or commercial objective.
• Nano particle size: At least one dimension (height, length or depth)
is less than 100s nm.

7. Techniques of Nanotechnology
 Top- Down Technique
 Bottom-up Technique

10. Synthesis of Nanoparticles by Sol-Gel
Method
■ The sol- gel process involves the evolution of inorganic networks through the
formation of a Colloidal suspension (sol) and gelation of the sol to form a network in
a continuous liquid phase (gel)
■ Sol--- Solid in Liquid
■ Gel---- Liquid in solid
■ The precursors (starting Material) is a metal or metalloid element surrounded by
various reactive ligands. For example– Tetraethyl orthosilicate [Si(OET)4. ]

12. SYNTHESIS OF NANOMATERIALS
Sol- Gel Method- the steps involved are:
■ Sol Gel process refers to the hydrolysis and condensation of alkoxide based precursors .
1. Hydrolysis and condensation of metal alkoxide precursors can be explained as follows:
M-O-R + H2O MOH + ROH (Hydrolysis)
MOH + R-O-M M-O-M + ROH (Condensation)
2. Gelation results from the formation of an oxide or alcohol bridged network by poly
condensation reaction that results in a dramatic increase in the viscosity of the solution.
3. Ageing of the gel or syneresis during which the poly condensation reactions continue until
the gel transforms into a solid mass , accompanied by contraction of the gel network and
expulsion of solvent from gel pores. The aging process of gel can exceed 7 days of time.
4. Dehydration, during which the surface bound M-OH groups are removed. This is done by
calcination of the monolith at temperature upto 8000 C.
5. Densification and decomposition of the gel at high temp. The pore of the gel network are
collapsed and remaining organic species are volatilized.

15. Aerogel : Aerogel is a synthetic porous
ultralight material derived from a gel, in
which the liquid component for the gel has
been replaced with a gas. The result is a
solid with extremely low density and
extremely low thermal conductivity.

16. An aerogel is obtained when the liquid phase of a gel* is replaced by a
gas in such a way that its solid network is retained, with only a slight or no
shrinkage in the gel. It was firstly achieved under supercritical conditions
but it is now possible under ambient drying conditions as well.
Shrinkage < 15%
A Xerogel (not to be confused by X-Aerogel) is obtained when the liquid
phase of a gel* is removed by evaporation. It may retain its original shape,
but often cracks due to the extreme shrinkage that is experienced while
being dried.
Shrinkage >90%
Therefore the method of drying will dictate whether an aerogel or xerogel
will be formed.

17. PRECIPITATION METHOD:
■ An Inorganic metal salt such as chlorides, nitrate, acetate is dissolved in water.
■ To these solutions, basic solutions such as NaOH, NH4OH are added. The species
undergo hydrolysis to form “Metal hydroxide ppt”.
■ The ppt is then washed with distilled water, filtered, dried and calcined at high
temperature to got final metal oxide nano powder.
■ Advantages 1) The process is relatively economical 2) By this method single and
multi component oxide nano powders can be synthesized.
■ Applications: By this method, ZnS nano powder, ZnO nano powder, Al2O3 nano
powder are synthesized.

18. Advantages and Disadvantages:
■ Advantages:
 Nanomaterials can be prepared at low temperature
 Nanomaterials with high purity can be prepared
 Nanoparticles with different size and morphology can be synthesized by varying synthesis
parameters.
 Disadvantages:
 Controlling the particle size is difficult
 Stopping the newly formed particles from agglomeration is difficult
 Production rates of nano powders by this method are very low.

19. Nanotechnology
 Nanotechnology is the understanding and control of matter at dimensions of roughly 1 to 100
nanometres, where unique phenomena enable novel applications.

20. HISTORY OF NANOTECHNOLOGY:

22. Fullerenes or Bucky Balls

24. Fullerenes are an allotropic form of carbon, consisting of
pure carbon atoms. A well-known example is C60, which is
shaped like a football, so metal ions and other active agents
can be enclosed in the inner cavity. Furthermore, fullerenes
themselves can act as a guest molecule in complexes with
macrocyclic ligands such as cyclodextrins.

25. PROPERTIES OF FULLERENES

27. Applications :
The potential biomedical applications of fullerenes
include antiviral activity, photosensitivity, anti
oxidation, anti-apoptosis, drug carriers, gene carriers,
diagnostics, and tissue engineering scaffolds.
Fullerenes and fullerene derivatives have a unique
molecular structure that can bind protease to exert an
antiviral effect
The exploration for the biomedical applications of
fullerenes started in 1993 when Friedman et al.
discovered that the hydrophobic gap in HIV-1 protease
could be tightly packed with C60 molecules, and
through the formation of protease-fullerene complex,
lead to enzyme inactivation and elimination of the
viral activities

29. Fullerenes can be used in
1. Superconductors
2. Electronic devices
3. Catalytic activities
4. Nano reactors
5. Biosensors

41. Applications of Graphene.

49. Properties and Applications
Properties:
•It is the world’s thinnest and strongest material
•It conducts heat better than all materials. It is a great conductor of
electricity
•It is optically transparent
•It is very dense and impermeable to gases
Applications:
• It is used in the manufacture of unbreakable smart phones, watches,
tennis racquet, fast rechargeable batteries.
•It is used in the manufacture of desalination membranes, surgical
equipment, artificial implants
•It is used in manufacture of super bullet proof vests long lasting industrial
lubricants
•Used in the manufacture of computer chips, solar cells, electric cars etc.

50. Introduction on Carbon Nanomaterials
• Carbon is one of the very interesting elements
which constitutes a major part of the living as
well as non-living world.
• Clusters and Nanomaterials that we know
today provide a rich variety of Carbon forms.
• Crystalline carbon can exist in diamond,
graphite, fullerene, carbon nanotubes,
graphene etc.
Types of Carbon nanomaterials
• Small Clusters, Fullerenes
and Nanodiamonds. 0-D
1-D • Carbon Nanotubes
2-D • Graphene and Graphane
3

51. Carbon Nano Tubes
• This 1-D form of carbon was accidentally
observed in 1991 by S. Iijima under a
transmission electron microscope. He was
actually examining some sample of carbon
clusters viz. ‘fullerenes’ synthesized using
electric arc discharge method.
• Further it was found that not only carbon but
many other materials like ZnO, TiO2, and MoS2
can have shape of nanotube

52. • Carbon nanotubes can be considered as cylinders
made of graphite sheets, mostly closed at the
ends, with carbon atoms on the apexes of the
hexagons, just like on a graphite sheet.
• One can consider carbon nanotube as folding of a
graphite sheet (it is only an imaginary sheet,
actual growth can be different), just like one rolls
a piece of paper into a cylindrical form.
• The difference however is that, a paper is a
two dimensional solid material (area much
larger, a few cm2, as compared to thickness of
few micrometres) and the graphite sheet we
are talking about has an area of few μm2 and
thickness just the atomic size of a Carbon
Atom.

54. If we consider the rolling of graphite sheet, we
can imagine carbon atoms being spread in
hexagonal arrangement with some lattice
strain.
• The lines showed connecting the filled spheres
(carbon) are the bonds that exist between the
atoms.
• Besides, during their formation, nanotubes
get capped with hemispheres of fullerenes.

55. Types of CNTs
•D – 1-2nm SWCNTs
•D – 2-25 nm
•More common
MWCNTs