Hierarchical Structures in Biology as a Guide for New Materials Technology (1994) / Chapter Skim
Currently Skimming:
EXECUTIVE SUMMARY
EXECUTIVE SUMMARY
Pages 1-12
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 1... ...
Many materials systems found in nature exhibit combinations of properties not currently found in synthetic systems. The unique performance of natural materials arises from precise hierarchical organization over a large range of length scales.
|
From page 2... ...
collagen) , such that widely variable properties are attained from apparently similar elementary units; controlled orientation of structural elements; durable interfaces between hard and soft materials; sensitivity to and critical dependence on-the presence of water; properties that vary in response to performance requirements; fatigue resistance and resiliency; controlled and often complex shapes; and capacity for self-repair.
|
From page 3... ...
When synthetic materials are manufactured with an emphasis on tailoring their properties through microstructural control, the extent of this control is generally at a specific length scale. For instance, the mechanical properties of most metallic materials are controlled through the manipulation of dislocation dynamics at the nanometer length scale, whereas the mechanical properties of ceramic materials are controlled through the propagation of cracks that are initiated from defects of micrometer length scales.
|
From page 4... ...
The hierarchical architectures of biological materials systems rely on critical interfaces that link structural elements of disparate scale. The study of such systems reveals extraordinary combinations of performance properties, as well as limitations due to the modest thermal and chemical stabilities of biological molecules.
|
From page 5... ...
. The utility of many synthetic hierarchical materials is currently limited by the availability of fabrication technology, excessive fabrication times, and high cost for finished parts.
|
From page 6... ...
This methodology is powerful and may lead not only to the creation of polymeric materials with functions not obtainable through conventional synthetic methods but also to an understanding of how control of molecular structure and function can impact improved materials performance. It is clear, however' that the thermal and hydrolytic sensitivities of proteinaceous materials will limit their usefulness in many important synthetic materials applications.
|
From page 7... ...
For example, the nacreous material in mollusk shell is a segmented composite with a very low volume fraction of matrix phase in very thin layers. The ability to design and fabricate synthetic structures with similar characteristics, as well as the ability to mimic adhesion between the phases, could lead to composites with remarkable
|
From page 8... ...
The committee feels that exposing the physical and chemical principles that underlie the special features of these materials is certain to stimulate new approaches to design of synthetic materials, parts, and systems. Such approaches may include preparation of "self-healing" capsular materials that possess tunable and motile properties; general methods for assembly of soft organic and hard material interfaces that are mechanically, chemically, and electrically compatible; and development of membrane composites that
|
From page 9... ...
TECHNOLOGICAL OPPORTUNITIES Biomedical Materials There is a recognized societal and economic need for synthetic materials with appropriate mechanical and functional performance characteristic properties for use in biomedical applications. The challenges in developing a manufacturing process to produce synthetic hierarchical materials with these required mechanical properties and functional characteristics are great.
|
From page 10... ...
Development of gels that are strong, cohesive, porous, permeable, and resorbable and that are capable of sustaining high stresses and strains and providing a supporting and protecting environment for the seeded cells is a major challenge for future biomedical researchers interested in developing synthetic hierarchical materials for clinical use. Improved Membranes and Membrane-based Devices Improved membrane selectivity is desirable in the areas of water purification, clothing to protect those handling hazardous materials, outdoor clothing and shelters, gas separations, industrial purification processes, etc.
|
From page 11... ...
Passively smart materials respond to external change without assistance often through phase changes or transitions in fundamental properties. Actively smart materials utilize feedback loops to recognize changes and initiate appropriate responses.
|
From page 12... ...
The biggest challenge is to scale the processes to practical size components while maintaining the precise control and consistency needed. The study of gradients in natural materials may provide direction for architectural design, fabrication processes, and potential applications for synthetic FGMs.
|
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.