Guozhong Cao. Nanostructures & Nanomaterials: Synthesis, Properties & Applications
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NANOSTRUCTURES
&
NANOMATERIALS
Synthesis, Properties
G;Z:
Applications
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University
of
Washington,
USA
NANOSTRUCTURES
&
NANOMATERIALS
Synthesis,
Properties
&
Applications
Imperial College Press
Guozhong Cao
Published by
Imperial College
Press
57
Shelton Street
Covent Garden
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British Library Cataloguing-in-Publication Data
A
catalogue record for this book is available from the British Library.
NANOSTRUCTURES AND NANOMATERIALS
Synthesis, Properties,
and
Applications
Copyright
0
2004 by Imperial College Press
All
rights reserved. This book,
or
parts thereof, muy not be reproduced in any
form
or
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or
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ISBN
1-86094-4159
ISBN
1-86094-480-9 (pbk)
Printed
in
Singapore
by
World Scientific Printers
(S)
Pte Ltd
Preface
Nanotechnology is design, fabrication and application of nanostructures
or nanomaterials, and the fundamental understanding of the relationships
between physical properties or phenomena and material dimensions.
Nanotechnology deals with materials or structures in nanometer scales,
typically ranging from subnanometers to several hundred nanometers.
One nanometer is
1
0-3
micrometer or meter. Nanotechnology is a
new field or a new scientific domain. Similar to quantum mechanics, on
nanometer scale, materials or structures may possess new physical prop-
erties or exhibit new physical phenomena. Some of these properties are
already known. For example, band gaps of semiconductors can be tuned
by varying material dimension. There may be many more unique physical
properties not known to
us
yet. These new physical properties or phe-
nomena will not only satisfy everlasting human curiosity, but also prom-
ise new advancement in technology. For example, ultra-strong ultra-light
multifunctional materials may be made from hierarchical nanostructures.
Nanotechnology also promises the possibility of creating nanostructures
of metastable phases with non-conventional properties including super-
conductivity and magnetism. Yet another very important aspect of nan-
otechnology is the miniaturization
of
current and new instruments,
sensors and machines that will greatly impact the world we live in.
Examples of possible miniaturization are: computers with infinitely great
power that compute algorithms to mimic human brains, biosensors that
warn us at the early stage of the onset of disease and preferably at the
molecular level and target specific drugs that automatically attack the dis-
eased cells on site, nanorobots that can repair internal damage and remove
V
vi
Preface
chemical toxins in human bodies, and nanoscaled electronics that con-
stantly monitor our local environment.
Nanotechnology has an extremely broad range of potential applications
from nanoscale electronics and optics, to nanobiological systems and
nanomedicine, to new materials, and therefore it requires formation of and
contribution from multidisciplinary teams of physicists, chemists, materi-
als scientists, engineers, molecular biologists, pharmacologists and others
to work together on (i) synthesis and processing of nanomaterials and
nanostructures, (ii) understanding the physical properties related to the
nanometer scale, (iii) design and fabrication of nano-devices or devices
with nanomaterials as building blocks, and (iv) design and construction of
novel tools for characterization of nanostructures and nanomaterials.
Synthesis and processing of nanomaterials and nanostructures are the
essential aspect of nanotechnology. Studies on new physical properties and
applications of nanomaterials and nanostructures are possible only when
nanostructured materials are made available with desired size, morphology,
crystal and microstructure and chemical composition. Work on the fabri-
cation and processing of nanomaterials and nanostructures started long
time ago, far earlier than nanotechnology emerged as a new scientific field.
Such research has been drastically intensified in the last decade, resulting
in overwhelming literatures in many journals across different disciplines.
The research on nanotechnology is evolving and expanding very rapidly.
That makes it impossible for a book of this volume to cover all the aspects
of the field. The readers will readily find that this book has been focused
primarily on inorganic materials. However, efforts were made to include
the relevant organic materials such as self-assembled monolayers and
Langmuir-Blodgett films. Of course, in the synthesis and processing of
nanomaterials, organic materials often play an indispensable role, such as
surfactants in the synthesis of ordered mesoporous materials, and capping
polymers in the synthesis of monodispersed nanoparticles. The aim of this
book is to summarize the fundamentals and established techniques
of
syn-
thesis and processing of nanomaterials and nanostructures
so
as to provide
readers a systematic and coherent picture about synthesis and processing
of nanomaterials. In addition, the last two chapters of the book have been
devoted to characterization, properties and applications of nanomaterials
and nanostructures. This book would serve as a general introduction to
people just entering the field, and also for experts seeking for information
in other subfields. This is not a handbook with quick recipes for synthesis
and processing of nanomaterials; it has been the intention of the author that
this book is to be a tutorial and not a comprehensive review. Therefore, this
Preface
vii
book is well suited as a textbook for upper-level undergraduate, graduate
and professional short courses.
The contents benefit greatly from the interaction between the author
and colleagues or students. Most of the subjects covered in this book have
been taught as a short course in
2002
SPIE
annual meeting and a regular
graduate course at the University of Washington. The precious feedback
from the students who attended the classes have been incorporated into
this book.
I
am grateful in particular to Mary Shang who took care of the
figures and went through all the details to clarify many points in the pres-
entation.
I
am also indebted to Ying Wang and Steven Limmer who got all
the copyright permission and helped in preparing some of the figures.
Our
department chair, Prof. Raj Bordia, is acknowledged for having graciously
reduced my department committee work. Editors, Mr. Stanford Chong and
Ms. Lakshmi Narayanan at World Scientific Publishing and Imperial
College Press are acknowledged for initiating and editing the book,
respectively. The writing of this book started coincidently with the birth of
my
son,
Doran, and finished when he turned a year old.
It
has been excit-
ing to see both the little boy and the manuscript grow at the same time.
This book would not have been possible without the dedication of my
mother-in-law, who left Hong Kong to come to the States to take care of
our son. My wife, Yuk Lan Li, deserves special thanks for her support and
understanding.
Guozhong Cao
Seattle,
WA
August
2003
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Contents
Preface
V
1. Introduction
1.1.
Introduction
1.2. Emergence of Nanotechnology
1.3. Bottom-Up and Top-Down Approaches
1.4. Challenges in Nanotechnology
1.5. Scope of the
Book
References
2.
Physical Chemistry of Solid Surfaces
2.1. Introduction
2.2. Surface Energy
2.3. Chemical Potential as a Function
of
Surface Curvature
2.4. Electrostatic Stabilization
2.4.1. Surface charge density
2.4.2. Electric potential at the proximity of solid surface
2.4.3. Van der Waals attraction potential
2.4.4. Interactions between two particles: DLVO theory
2.5.1. Solvent and polymer
2.5.2. Interactions between polymer layers
2.5.3. Mixed steric and electric interactions
2.5. Steric Stabilization
2.6. Summary
References
1
1
4
7
10
11
14
15
15
17
26
32
32
33
36
38
42
43
45
47
48
48
ix