O o d h e a d p u b L i s h I n g L i m I t e d

Nanotechnologies  are the design, characterisation, production and
application of structures, devices and systems by controlling shape and
size at nanometre scale.
Nanotechnology involves the creation or manipulation of structures at the
nanoscale. At this scale the characteristics of matter can be dominated by
quantum effects, molecular recognition, confinement effects and increases
in relative surface area. This can result in significant differences in behaviour
of materials at the nanoscale when compared to the bulk material (Renn and
Roco, 2006). Gold nanoparticles for example range in colour from deep red
at 7–20 nm to blue at approximately 300 nm and finally gold in the bulk
material.
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For textile applications, nanotechnology is more than applying very thin
coatings or small particles to fibre substrates. It is changing the properties of
the fibre in a way that cannot be achieved by applying bulk materials or thin
films to the fibre surface.
10.1.1 Principles of nanotechnology
The nanometre scale is used to describe objects having at least one dimension
between 1 and 100 nm. The Greek word ‘nano’, which means dwarf, is used
as a prefix meaning one billionth or 10
–9
, hence one nanometre (nm) is one
billionth of a metre or approximately 20 000 times smaller than a 20
µm
wool fibre. A cubic nanometre (nm
3
) can contain approximately 20 atoms.
Some typical objects in the nanoscale range are shown in 
Figure 10.1.
Nanotechnology development has been described in terms of four
generations (Roco, 2006) as listed in 
Table 10.1.
 The current generation, and
most applicable to wool textiles, is the first generation, involving passive
nanostructures in which the nanomaterials perform a single function. Later
generations of nanotechnology will perform multiple functions and involve
several nanotechnologies integrated into a single system.
Although first generation nanotechnology is usually the application of
nanoparticles, the emerging consensus is that nanotechnology involves the
control and restructuring of matter at the nanoscale leading to engineered
functional systems at the molecular scale.
10.1.2 Introduction to nanoparticles and
nano-emulsions
Nanoparticles are the building blocks of nanotechnology. They are available
in a range of common shapes including spheres, rods, tetrahedrons, octahedrons
and discs. Nanoparticles are characterised by a high surface to bulk atom
ratio, which often results in enhanced chemical activity. Qi et al. (2004)
ST microscope< SE microscope
< Optical microscope
1 nm
10 nm
100 nm
1000 nm
10 000 nm
1
µm
10
µm
Nanoparticles
Nanotubes
Nanofibres
Microfibres
Wool
Bacteria
Virus
 Ionic molecular
Macromolecular
Micro
10.1
 Some typical objects in the nanoscale range (ST = scanning
transmission, SE = scanning electron).
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calculated the shape factor for several nanoparticle shapes, which can be
used to calculate the ratio of surface to total atoms using equation 10.1:
N/n = 4
αd/D
10.1
where N/n is the ratio of surface to total atoms in the particle, d is the atomic
diameter and D is the particle diameter. The shape factor, 
α, was calculated
for a number of shapes. Examples of shape factors and percentage surface
atoms for a number of nanoparticle shapes are shown in 
Table 10.2
 and 
Fig.
10.2.
 The data were calculated for the disc-shaped particle, assuming the
radius of the disc was twice the height.
The very high percentage of surface atoms of nanoparticles, particularly
those less than 20 nm in diameter, results in many properties that differ from
Table 10.1 The generations of nanotechnology as defined by Roco and examples
Generations
Description
Examples
First
Passive nanostructures
• Dispersed and contact
Colloids, nanoparticles, aerosols,
nanostructures
nanotubes
• Products incorporating
Coatings, nanoparticle reinforced
nanostructures
composites, nanostructure
metals and polymers
Second
Active nanostructures
• Bioactive materials that
Targeted drugs and delivery
change function during use
systems, biodevices
• Physico-chemical active
Amplifiers, actuators, adaptive
structures, sensors and control
systems
Third
Integrated nanosystems
• Passive and/or active
Artificial organs built from the
nanostructures integreated
nanoscale, evolutionary
into systems
nanobiosystems, hybrid systems,
3D networking
• Convergence of
nanotechnology,
biotechnology, information
technology and the
cognitive sciences
Fourth
Molecular nanosystems
Self-assembling products,
• Engineered nanosystems
nanoscale genetics,
and architectures created
nanosystems integrated
from individual molecules
with industrial applications,
or supramolecular
atomic design
components each with a
specific structure and role
• The behaviour of
applications being based on
that of biological systems
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the bulk material. For example, the high curvature of nanoparticles results in
an increase in surface energy that affects the interior bulk properties of the