Lecture-1
INTRODUCTION TO NANOMATERIALS
1. Introduction
Nanomaterials are cornerstones of nanoscience and nanotechnology. Nanostructure
science and technology is a broad and interdisciplinary area of research and development
activity that has been growing explosively worldwide in the past few years. It has the
potential for revolutionizing the ways in which materials and products are created and the
range and nature of functionalities that can be accessed. It is already having a significant
commercial impact, which will assuredly increase in the future.
Fig. 1. Evolution of science and technology and the future
, 1.1. What are nanomaterials?
Nanoscale materials are defined as a set of substances where at least one dimension is
less than approximately 100 nanometers. A nanometer is one millionth of a millimeter -
approximately 100,000 times smaller than the diameter of a human hair. Nanomaterials
are of interest because at this scale unique optical, magnetic, electrical, and other
properties emerge. These emergent properties have the potential for great impacts in
electronics, medicine, and other fields
.
Fig. 2. Nanomaterial (For example: Carbon nanotube)
,1.2. Where are nanomaterials found?
Some nanomaterials occur naturally, but of particular interest are engineered
nanomaterials (EN), which are designed for, and already being used in many commercial
products and processes. They can be found in such things as sunscreens, cosmetics,
sporting goods, stain-resistant clothing, tires, electronics, as well as many other everyday
items, and are used in medicine for purposes of diagnosis, imaging and drug delivery.
Engineered nanomaterials are resources designed at the molecular (nanometre)
level to take advantage of their small size and novel properties which are generally not
seen in their conventional, bulk counterparts. The two main reasons why materials at the
nano scale can have different properties are increased relative surface area and new
quantum effects. Nanomaterials have a much greater surface area to volume ratio than
their conventional forms, which can lead to greater chemical reactivity and affect their
strength. Also at the nano scale, quantum effects can become much more important in
determining the materials properties and characteristics, leading to novel optical,
electrical and magnetic behaviours.
Nanomaterials are already in commercial use, with some having been available
for several years or decades. The range of commercial products available today is very
broad, including stain-resistant and wrinkle-free textiles, cosmetics, sunscreens,
electronics, paints and varnishes. Nanocoatings and nanocomposites are finding uses in
, diverse consumer products, such as windows, sports equipment, bicycles and
automobiles. There are novel UV-blocking coatings on glass bottles which protect
beverages from damage by sunlight, and longer-lasting tennis balls using butyl-
rubber/nano-clay composites. Nanoscale titanium dioxide, for instance, is finding
applications in cosmetics, sun-block creams and self-cleaning windows, and nanoscale
silica is being used as filler in a range of products, including cosmetics and dental
fillings.
2. Advances in Nanomaterials
The history of nanomaterials began immediately after the big bang when Nanostructures
were formed in the early meteorites. Nature later evolved many other Nanostructures like
seashells, skeletons etc. Nanoscaled smoke particles were formed during the use of fire
by early humans. The scientific story of nanomaterials however began much later. One of
the first scientific report is the colloidal gold particles synthesised by Michael Faraday as
early as 1857. Nanostructured catalysts have also been investigated for over 70 years. By
the early 1940’s, precipitated and fumed silica nanoparticles were being manufactured
and sold in USA and Germany as substitutes for ultrafine carbon black for rubber
reinforcements.
Nanosized amorphous silica particles have found large-scale applications in many
every-day consumer products, ranging from non-diary coffee creamer to automobile tires,
optical fibers and catalyst supports. In the 1960s and 1970’s metallic nanopowders for
magnetic recording tapes were developed. In 1976, for the first time, nanocrystals
produced by the now popular inert- gas evaporation technique was published by
Granqvist and Buhrman. Recently it has been found that the Maya blue paint is a
nanostructured hybrid material. The origin of its color and its resistance to acids and
biocorrosion are still not understood but studies of authentic samples from Jaina Island
show that the material is made of needle-shaped palygorskite (clay) crystals that form a
superlattice with a period of 1.4 nm, with intercalates of amorphous silicate substrate
containing inclusions of metal (Mg) nanoparticles. The beautiful tone of the blue color is
obtained only when both these nanoparticles and the superlattice are present, as has been
shown by the fabrication of synthetic samples.
INTRODUCTION TO NANOMATERIALS
1. Introduction
Nanomaterials are cornerstones of nanoscience and nanotechnology. Nanostructure
science and technology is a broad and interdisciplinary area of research and development
activity that has been growing explosively worldwide in the past few years. It has the
potential for revolutionizing the ways in which materials and products are created and the
range and nature of functionalities that can be accessed. It is already having a significant
commercial impact, which will assuredly increase in the future.
Fig. 1. Evolution of science and technology and the future
, 1.1. What are nanomaterials?
Nanoscale materials are defined as a set of substances where at least one dimension is
less than approximately 100 nanometers. A nanometer is one millionth of a millimeter -
approximately 100,000 times smaller than the diameter of a human hair. Nanomaterials
are of interest because at this scale unique optical, magnetic, electrical, and other
properties emerge. These emergent properties have the potential for great impacts in
electronics, medicine, and other fields
.
Fig. 2. Nanomaterial (For example: Carbon nanotube)
,1.2. Where are nanomaterials found?
Some nanomaterials occur naturally, but of particular interest are engineered
nanomaterials (EN), which are designed for, and already being used in many commercial
products and processes. They can be found in such things as sunscreens, cosmetics,
sporting goods, stain-resistant clothing, tires, electronics, as well as many other everyday
items, and are used in medicine for purposes of diagnosis, imaging and drug delivery.
Engineered nanomaterials are resources designed at the molecular (nanometre)
level to take advantage of their small size and novel properties which are generally not
seen in their conventional, bulk counterparts. The two main reasons why materials at the
nano scale can have different properties are increased relative surface area and new
quantum effects. Nanomaterials have a much greater surface area to volume ratio than
their conventional forms, which can lead to greater chemical reactivity and affect their
strength. Also at the nano scale, quantum effects can become much more important in
determining the materials properties and characteristics, leading to novel optical,
electrical and magnetic behaviours.
Nanomaterials are already in commercial use, with some having been available
for several years or decades. The range of commercial products available today is very
broad, including stain-resistant and wrinkle-free textiles, cosmetics, sunscreens,
electronics, paints and varnishes. Nanocoatings and nanocomposites are finding uses in
, diverse consumer products, such as windows, sports equipment, bicycles and
automobiles. There are novel UV-blocking coatings on glass bottles which protect
beverages from damage by sunlight, and longer-lasting tennis balls using butyl-
rubber/nano-clay composites. Nanoscale titanium dioxide, for instance, is finding
applications in cosmetics, sun-block creams and self-cleaning windows, and nanoscale
silica is being used as filler in a range of products, including cosmetics and dental
fillings.
2. Advances in Nanomaterials
The history of nanomaterials began immediately after the big bang when Nanostructures
were formed in the early meteorites. Nature later evolved many other Nanostructures like
seashells, skeletons etc. Nanoscaled smoke particles were formed during the use of fire
by early humans. The scientific story of nanomaterials however began much later. One of
the first scientific report is the colloidal gold particles synthesised by Michael Faraday as
early as 1857. Nanostructured catalysts have also been investigated for over 70 years. By
the early 1940’s, precipitated and fumed silica nanoparticles were being manufactured
and sold in USA and Germany as substitutes for ultrafine carbon black for rubber
reinforcements.
Nanosized amorphous silica particles have found large-scale applications in many
every-day consumer products, ranging from non-diary coffee creamer to automobile tires,
optical fibers and catalyst supports. In the 1960s and 1970’s metallic nanopowders for
magnetic recording tapes were developed. In 1976, for the first time, nanocrystals
produced by the now popular inert- gas evaporation technique was published by
Granqvist and Buhrman. Recently it has been found that the Maya blue paint is a
nanostructured hybrid material. The origin of its color and its resistance to acids and
biocorrosion are still not understood but studies of authentic samples from Jaina Island
show that the material is made of needle-shaped palygorskite (clay) crystals that form a
superlattice with a period of 1.4 nm, with intercalates of amorphous silicate substrate
containing inclusions of metal (Mg) nanoparticles. The beautiful tone of the blue color is
obtained only when both these nanoparticles and the superlattice are present, as has been
shown by the fabrication of synthetic samples.
