分子杠杆可使材料效能更好
- 指点迷津
- 2024-11-30
- 10
In a forced game of
molecular
1 tug-of war, some
strings
2 of atoms can act like a
lever(杠杆), accelerating reactions 1000 times faster than other
molecules
4. The discovery suggests that scientists could use these molecular levers to drive chemical and mechanical reactivity among atoms and ultimately engineer more efficient materials. "We are interested in designing new, stress-responsive materials, so we are trying to develop reactions that are very slow normally but that can be accelerated
efficiently
5 by force," said Duke chemist Steve Craig, who headed the research., ,In recent experiments, Craig and his team found that a
molecule
3 made with a
polynorbornene(聚降冰片烯)
backbone
6 can act as a lever to open a ring
embedded
7 within the molecule 1000 times faster than a similar ring being
tugged
8 at on a
polybutadiene(聚丁二烯) scaffold. The results, which appear Dec. 23 in Nature Chemistry, suggest that a simple change in the backbone may affect the how fast mechanically assisted reactions occur., ,Scientists are interested in this type of molecular tug-of-war because many materials break down after repeated cycles of
tugging
9, stress and other forces. "If we can channel usually destructive forces into
constructive
10 pathways, we could trigger reactions that make the material stronger when and where it is most useful," Craig said. Researchers might then be able to extend the material's lifetime, which might in the long term have applications ranging from composites for airplane frames to biomedical
implants
11., ,In the experiment, Craig, who is a professor and chair of the chemistry department, and his team used the equivalent of
microscopic
12
tweezers13(镊子,小钳子) to grab onto two parts of atomic chains and pulled them so that they would break open, or react, in certain spots. The team predicted that one molecule would react more efficiently than the other but was surprised to find that the force-induced rates differed by three orders of magnitude, an amount that suggests that the polynorbornene backbone can actually accelerate forced reactions the way a
crowbar(撬棍) quickens pulling a nail from a wall., ,Craig said changes to the molecular group undergoing the reaction may have a much smaller effect than changes to nearby, unreactive molecules like those on the backbone. It is also a good starting point to identify other molecular
backbones
14 that are easy to make and have the largest response to changes in nearby reactions, features Craig said might help in developing even better, more responsive materials., ,The research was supported by the U.S. Army Research Laboratory, the Army Research Office and National Science Foundation.
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