Beyond the Molecular Frontier Challenges for Chemistry and Chemical Engineering (2003) / Chapter Skim
Currently Skimming:
8 Materials by Design
8 Materials by Design
Pages 123-147
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 123... ...
8 Materials by Design1 1As part of the overall project on Challenges for the Chemical Sciences in the 21st Century, a workshop on Materials and Manufacturing will lead to a separate report. The reader is urged to consult that report for further information.
|
From page 124... ...
A frontier challenge in the chemical sciences is to investigate the chemistry and properties of single isolated molecules and compare that behavior with the average molecular behavior in an assembly, solution, or condensed phase of molecules. Many parts of the chemical sciences are concerned with the collective properties of materials in condensed phases, which have a variety of intriguing and controllable properties.
|
From page 125... ...
Our abilities to achieve these goals in new materials synthesis are enhanced by intricate optical, micromechanical, and spectroscopic probes, just as they are by the use of noncovalent bonding, self-assembly, and assembly directed by forces such as fluid mechanical or electric fields. The miniaturization and diversification of synthesis through biological or combinatorial approaches provide unprecedented opportunities.
|
From page 126... ...
One of the earliest synthetic materials is glass, produced over 5,000 years ago by heating various natural minerals together. Clearly, the discovery, refinement, and creation of materials has arisen from the chemical sciences and processing technology (and sometimes vice versa)
|
From page 127... ...
So-called liquid crystals illustrate another exciting example of complex fluid materials; these are liquid-phase materials made up of anisotropic, usually fairly rigid, molecules of high aspect ratio that have strong electric dipole moments. Such molecules are prone to adopt preferred orientations, especially under the influence of surfaces, electric fields, and flow processes.
|
From page 129... ...
MATERIALS BY DESIGN ~1 Metal Film b)
|
From page 130... ...
Combining this activity with concerted synthetic chemistry and biochemistry provides great potential for the future. Electronic, Optoelectronic, Photonic, Magnetic, and Superconducting Materials The properties of modern electronic, optoelectronic, photonic, and magnetic devices provide another story of great science that has affected most of humankind.
|
From page 131... ...
The materials studied to date are also difficult to process they are easily corroded or brittle thus motivating further study of novel processing or assembly techniques. If practical superconductors can be made that will conduct appreciable currents at reasonable temperatures perhaps even from organic materials it may become possible to transfer electric power over long distances with high efficiency, and to exploit magnetic levitation for transportation systems.
|
From page 132... ...
132 ¢ ._ o ._ V: SO Cal o o V .— I C)
|
From page 133... ...
MATERIALS BY DESIGN 133 Ceramics, Carbon Structures, and Crystal Engineering inorganic substances are the components of ceramics, such as those in dinner plates. Ceramics have important industrial uses as well; a typical example is the ceramic insulating materials that are used to suspend power lines.
|
From page 134... ...
A challenge for the future is to invent improved structural materials, probably composites based on resins or on ceramics, that are stable at high temperatures and easily machined. Carbon atoms in pure form can be obtained as materials having two classic types of molecular structure: diamond and graphite.
|
From page 135... ...
Learning to template or guide desired organization of molecules will have great utility. Layered Materials and Surface Modification The scale of components in complex condensed matter often results in structures having a high surface-area-to-volume ratio.
|
From page 136... ...
, plasma processing, etching, and electroless deposition. Nanomaterials As the analytical, synthetic, and physical characterization techniques of the chemical sciences have advanced, the scale of material control moves to smaller sizes.
|
From page 137... ...
These techniques arise from four approaches, and their simultaneous applicability to a common set of targets is one of the reasons for the excitement in the field. The first set includes the classical techniques developed from microfabrication: · electron beam writing, which is the most important, although x-ray and deep UV photolithographies may also contribute; · use of scanning probe devices to move individual atoms or to write patterns; · preparation of colloids, vesicles, emulsions, buckytubes, and self-assembled monolayers using chemical self-assembly methods (some with histories that date back to the beginning of chemistry)
|
From page 138... ...
The miniaturization and diversification of synthesis through biological or combinatorial approaches provide unprecedented
|
From page 139... ...
However, the close interplay between chemical composition and physical interactions makes this a possibility; new synthetic approaches involving controlled living polymerizations and biological synthetic pathways allow control of molecular composition. Additional research on the balance of physical forces driving self-assembly, recognition, field responsive behavior, and biological compatibility should be closely tied to the synthetic efforts.
|
From page 140... ...
In this field, the chemical sciences will have to interact creatively with computer science and engineering in order to turn promising molecular switching ideas into practical computer architectures.
|
From page 141... ...
Surface Modification and Interfaces with Biology and Electronics The connection between biological function and a useful electrical signal is the capstone of sensor technology that will change medical, environmental, and personal-protection strategies in the coming decades. The link between biology and electronics is through the chemical sciences.
|
From page 142... ...
The free energy landscapes along the paths toward self-assembled products are not fully explored. Local minima and metastable states lurk but are uncharted, and it is often not appreciated when they are occupied or when they are trapping the process far from the desired equilibrium state.
|
From page 143... ...
For self-assembled macromolecular structures, these simulations can be approached from the atomic-molecular scale through the use of molecular dynamics or finite element analysis. Chapter 6 discusses opportunities in computational chemical science and computational materials science.
|
From page 144... ...
materials materials for which the electrical conductivity can change by a few percent under the application of an external magnetic field. GMR materials moved from a laboratory curiosity to the dominant technology in computer memories within a decade a startling example of how a new material can completely change a major industry.
|
From page 145... ...
will provide new capabilities of control and tuning of these complex fluids. Tools, Resources, and Infrastructures The area of complex condensed matter depends crucially on the availability of appropriate tools for both fabrication and characterization.
|
From page 146... ...
are the only methods that routinely provide nanometer resolution. In contrast to the mature instrumental techniques discussed above, a hitherto nonexistent class of techniques will require substantial development effort.
|
From page 147... ...
that depend essentially on advances in materials science and engineering. From synthesis to processing to commodity manufacturing of materials, the tools of chemical science and engineering will be essential to defining the next century in these terms.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.