































































Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community for help and clear up your study doubts
Discover the best universities in your country according to Docsity users
Free resources
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
EDWIN L. THOMAS, MASSACHUSETTS INSTITUTE OF TECHNOLOGY ... Supramolecular chemistry of polymers is an emerging area bridging chemistry, biolo-.
Typology: Study notes
1 / 71
This page cannot be seen from the preview
Don't miss anything!
On the cover:
1 Human Repair. Courtesy of National Geographic and Corel Corporation. 2 Cell Membrane Interactions with Electronic Materials. Courtesy of Aaron Amstutz, Beckman Institute, Urbana, Illinois. 3 Genetically Modifiable Plants for Polymer Synthesis. Courtesy of Crop Sciences, University of Illinois. 4 Towering Blown Film. Courtesy of Chris Macosko, University of Minnesota and Rheometric Scientific. 5 Polymer Light-Emitting Diodes. Courtesy of Conjugated Polymer Group, Linköping University. 6 ß-Sheet Assembly in Macromolecular Crystals. Courtesy of David Tirrell, University of Massachusetts. 7 Supramolecular Mushroom Nanostructure. Courtesy of Samuel Stupp and Aaron Amstutz, Beckman Institute, Urbana, Illinois. 8 Metallocene Catalyst. Courtesy of Robert Waymouth, Stanford University. 9 Self Assembly of Cone-Shaped Polymers into Nano-spheres. Courtesy of Virgil Percec, Case Western Reserve University.
and Dr. John W. Lightbody (Acting Director, Div. of Physics.) In the Directorate for Engineering, Dr. Elbert L. Marsh (Acting Assistant Director), Dr. Joseph E. Hennessey (Acting Deputy Assistant Director), Dr. Gary W. Poehlein (Director, Div. of Chemical and Transport Systems), Dr. Janie M. Fouke (Director, Div. of Bioengineering and Environmental Systems), Dr. Bruce M. Kramer (Director, Div. of Design, Manufacturing, and Industrial Innovation), and Dr. Ronald L. Sack (Director, Div. of Civil and Mechanical Systems.) In the Directorate for Biological Sciences, Dr. Mary E. Clutter (NSF Assistant Director), Dr. James L. Edwards (Deputy Assistant Director), Dr. Maryanna P. Henkart (Director, Div. of Molecular and Cellular Biosciences), Dr. Bruce L. Umminger (Director, Div. of Integrative Biology and Neuroscience.) In the Directorate for Education and Human Resources, Dr. John B. Hunt (Deputy Assistant Director), Dr. Karolyn K. Eisenstein (Senior Staff Associate, Div. of Undergraduate Education), and Dr. Herbert H. Richtol (Program Director, Div. of Undergraduate Education.) In the Directorate for Social, Behavioral, and Economic Sciences, Dr. Norbert M. Bikales (Head, NSF Europe Office.) I apologize if I inadvertently left out anyone else. Most importantly, I am extremely thankful to Andrew Lovinger for his dedication and commitment to this project. Finally, I would like to acknowlegde Verna Riley and Jeff Dalsin for their help in prepar- ing this report.
Samuel I. Stupp Workshop Chair
April 1998
3
A very exciting new field of interdisciplinary macromolecular science and engineering (MMSE) is rapidly emerging, a field at the crossroads of materials science/polymer sci- ence, engineering disciplines, chemistry, physics, and biology. MMSE is the area of sci- ence and engineering that studies substances composed of very large molecules such as those found in common plastics but also in biological structures, including genes and proteins. The origin of the field is the narrower area of polymer science and engineer- ing which grew over the past four decades around plastics technology. At the end of this century it is clear that our knowledge base in a number of disciplines including polymer science, chemistry, biology, and engineering is converging to initiate a new field that can exert a profound impact on the nation’s economy and quality of life.
4
involving the global environment.
General Recommendations
The workshop participants hope that NSF and other agencies will insure optimal devel-
6
opment of this critical field of interdisciplinary MMSE in the U.S. by funding both research and educational initiatives that specifically target the areas mentioned above. These ini- tiatives should include flexible modes of funding and proposal evaluation procedures to minimize the burden on the community.
EXECUTIVE S UMMARY • 7
9
Dr. Joseph Wirth, “Converting Polymer Science into Technology”
Coffee break
Subgroup discussions
Dinner
Subgroup discussions
Thursday, May 15
Subgroup discussions
Coffee break
Plenary Session , Samuel I. Stupp, Chair
Recommendations from Subgroup 1 and discussion, Prof. Robert Grubbs
Recommendations from Subgroup 2 and discussion, Dr. Scott Milner
Recommendations from Subgroup 3 and discussion, Prof. Lynn Jelinski
Recommendations from Subgroup 4 and discussion, Prof. David Tirrell
Recommendations from Subgroup 5 and discussion, Prof. Edwin Thomas
Lunch
Subgroup meetings to draft reports
Adjourn
Friday, May 16
Discussion of Workshop results by Organizing Committee
Coffee break
Meeting of Organizing Committee
Lunch
Meeting of Organizing Committee; draft of Report
10
12
Human Repair
For decades macromolecules in many different forms have played a key role in human repair. Blood vessels have been repaired with fabrics woven from fibers made of poly(ethylene terephthalate) — the same polymer found in beverage bottles and magnetic tapes. In recon - structed hip and knee joints, the most technologically common plastic — poly - ethylene — is used as the low friction surface that allows patients to move their limbs without pain after surgery. Very recently macromolecular artificial skins that are partly biodegradable have been developed for victims of serious burns. Many other examples in current use could be cited. Novel concepts in human repair using macromolecules are being researched in laboratories around the world, and one interesting example is the tissue engineering approach to regenerate diseased or broken bones, torn cartilage in our knees, and other structures. This approach utilizes sponge-like materials made of biodegradable macromolecules that are seeded with cells and proteins that could, in principle, regenerate the tissue of interest. Through research the future could deliver much more sophisticated concepts in human repair using molecu - larly designed macromolecular materials that interact with tissues in the body in a pre-engineered way. These novel forms of macromolecular matter could be designed to form perfect junctions with natural tissues and function as ideal replacements for parts of the human body in need of repair. Other forms will be cell seeded and biodegradable in a prescribed time, and would be able to change size and shape predictably to make way to the regenerated tissues they template as scaffolds. The contact of cells with nanoscale features on the
Human repair in the future will be done either with spe- cially designed synthetic materials (right side) or with materials that will mediate the regeneration of tissues (left side.)
B IOMATERIALS AND MACROMOLECULAR B IOLOGY • 13
scaffolds could regulate some of their func - tions, thus curing diseases, dissolving tumors, and mediating the growth of miss - ing tissues. Those advances will require nanoscale control of macromolecular struc - ture, a deeper understanding of self assem - bly, advances in molecular biology, and access to genetically engineered proteins.
B IOMATERIALS AND MACROMOLECULAR B IOLOGY • 15
Bio-inspiration from Spider Silk
Why spider silk?
Spider silk is a protein fiber with unusually good mechanical properties. Single fibers of spider dragline silk, about 1/15 the diameter of a human hair, have a tensile strength that rivals that of steel, yet the fibers stretch to more than 10% elongation before breaking.
Spider silk also combines a rea - sonably high stiffness with a very large extension to break, so that the toughness — the energy required to cause a tensile failure — is very high. The initial modu - lus of the fiber is greater than that of nylon-6,6, and more importantly, the fiber does not fail in compression by kinking, a feature that makes spider silk in some ways superior to the highest performance human-made fibers.
In addition, the mechanical prop - erties are achieved under extremely mild and environmentally benign processing conditions, and without extensive draw - ing of the fiber, unlike synthetic high per - formance fibers.
Finally, the spider system is ideal as a research vehicle because it repre - sents a set of evolutionarily tailored fibrous materials. Most of these materi - als are poorly understood and hold many insights to be discovered regarding struc - ture-function relationships and process - ing relevant to materials science.
Why now?
The tools of biotechnology now make it possible to produce genetically engineering silk-like proteins. Once the molecular basis for the excellent mechanical properties of silk is under-
Scientists are looking toward spider silks as a source of bio-inspiration for the production of a new class of high performance materials.
16
stood, we can produce synthetic DNA that codes for the correct sequences and express the proteins in bacteria or perhaps even in plants. There are still hurdles to overcome, though. One involves learning how the spider processes the fibers to pro - duce a highly oriented material, and some - how imitating that process in the laborato - ry. Another involves understanding the effect that water has on the mechanical properties, and engineering out of the pro - tein these deleterious effects.