Page 19 - Materials Chemistry, Second Edition

6 1 What Is Materials Chemistry?

The market price of a device is governed by the costs of its subunits. Shortly after
the invention of germanium-based transistors in the late 1940s, the price of an
individual transistor was approximately US $8–10. However, as germanium was
substituted with silicon, and fabrication techniques were improved, the price of these
materials has exponentially decreased to its current price of one-millionth of a
penny! This has allowed for an unprecedented growth in computational expediency,
without a concomitant increase in overall price.
There are two rationales for the synthesis of materials – “top-down” and “bottom-
up”; Figure 1.4 illustrates examples of materials synthesized from both approaches.
Whereas the transformation of complex natural products into desirable materials
occurs primarily via a top-down approach (e.g., gemstones from naturally occurring
mineral deposits, etching features on silicon wafers for chip production), the major-
ity of synthetic materials are produced using the bottom-up approach. This latter
technique is the easiest to visualize, and is even practiced by children who assemble
individual LEGO ™ building blocks into more complex architectures. Indeed, the
relatively new field of nanotechnology has drastically changed the conception of
bottom-up processes, from the historical approach of combining/molding bulk
precursor compounds, to the self-assembly of individual atoms and molecules.
This capability of being able to manipulate the design of materials from the atomic
level will provide an unprecedented control over resultant properties. This will open
up possibilities for an unlimited number of future applications, including faster
electronic devices, efficient drug-delivery agents, and “green” energy alternatives
such as hydrogen-based and fuel cell technologies.
The recent discovery of self-repairing/autonomic healing structural materials is an
example of the next generation of “smart materials.” Analogous to the way our
bodies are created to heal themselves, these materials are designed to undergo
spontaneous physical change, with little or no human intervention. Imagine a
world where cracks in buildings repair themselves, or automobile bodies actually
appear in showroom condition shortly following an accident. Within the next few
decades, these materials could be applied to eliminate defective parts on an assem-
bly line, and could even find use in structures that are at present impractical or
impossible to repair, such as integrated circuits or implanted medical devices. This is
the exciting world that lies ahead of us – as we learn more about how to reproducibly
design materials with specific properties from simple atomic/molecular subunits, the
applications will only be limited by our imaginations!

1.3. DESIGN OF NEW MATERIALS THROUGH
A “CRITICAL THINKING” APPROACH
Although it is essential to use critical thinking to logically solve problems, this
method of reasoning is not being taught in most baccalaureate and postbaccalaureate
curricula. Unfortunately, the curricular pattern is focused on memorization and
standardized-exam preparation. Further, with such a strong influence of television,