 |
|
A molecular ripcord for chemical reactions
April 07, 2009Researchers at Eindhoven University of Technology (TU/e) have developed an entirely new method for starting chemical reactions. For the first time they used mechanical forces to control catalytic activity - one of the most fundamental concepts in chemistry. This allowed them to initiate chemical reactions with mechanical force. This discovery paves the way to developing materials capable of repairing themselves under the influence of mechanical tension. The results of their research will be published online on 6 April 2009 in the new international journal Nature Chemistry.
Molecular ripcord
The research team (Dr. Alessio Piermattei, Dr. Karthik Sivasubramanian and Dr. Rint Sijbesma) of the Institute for Complex Molecular Systems (ICMS) and the Department of Chemical Engineering and Chemistry, both at TU/e, is the first to have demonstrated that a catalyst can be switched from a dormant to an active state (see illustration) by pulling on a polymer chain, a "molecular ripcord." The researchers were able to use this catalyst to initiate a variety of chemical reactions, including polymerizations (formation of polymer chains from small molecular building blocks called monomers).
Self-repairing materials
This discovery paves the way to creating self-repairing materials that strengthen under the influence of mechanical stress. If a material were to tear, for example, this would simultaneously break the metal complex in half, thereby activating the catalyst, and the material would be instantly repaired.
This work will also lead to research into other applications in which it should be possible to turn chemical reactions on and off as desired. Potential applications include the injection molding of plastic objects, where the technique could be used to simplify processing, or microscale chemical synthesis.
How does it work; weakest link
The researchers packed a catalytically active metal ion completely in using two molecular caps (ligands). They attached two polymer chains to these caps, creating a long chain with a metal complex in the center. These complexes were dissolved in a liquid that was irradiated with ultrasound, causing bubbles to form in the liquid. When these bubbles imploded, they created an extremely strong current that stretched the chains and ultimately broke its weakest link - the metal complex - in two. The cap on one end was now broken off from the active metal ion, which allowed the metal ion to become catalytically active. In other words, it could now accelerate chemical reactions.
Eindhoven University of Technology
Self-repairing materials
This discovery paves the way to creating self-repairing materials that strengthen under the influence of mechanical stress. If a material were to tear, for example, this would simultaneously break the metal complex in half, thereby activating the catalyst, and the material would be instantly repaired.
This work will also lead to research into other applications in which it should be possible to turn chemical reactions on and off as desired. Potential applications include the injection molding of plastic objects, where the technique could be used to simplify processing, or microscale chemical synthesis.
How does it work; weakest link
The researchers packed a catalytically active metal ion completely in using two molecular caps (ligands). They attached two polymer chains to these caps, creating a long chain with a metal complex in the center. These complexes were dissolved in a liquid that was irradiated with ultrasound, causing bubbles to form in the liquid. When these bubbles imploded, they created an extremely strong current that stretched the chains and ultimately broke its weakest link - the metal complex - in two. The cap on one end was now broken off from the active metal ion, which allowed the metal ion to become catalytically active. In other words, it could now accelerate chemical reactions.
Eindhoven University of Technology
Chemical Reactions Current Events and Chemical Reactions News RSSBiologists discover bacterial defense mechanism against aggressive oxygen
Bacteria possess an ingenious mechanism for preventing oxygen from harming the building blocks of the cell.
Vibrations key to efficiency of green fluorescent protein
University of California, Berkeley, chemists have discovered the secret to the success of a jellyfish protein whose green glow has made it the darling of biologists and the subject of the 2008 Nobel Prize in Physiology or Medicine.
Computer predicts reactions between molecules and surfaces, with 'chemical precision'
Good news for heterogeneous catalysis and the hydrogen economy: computers can now be used to make accurate predictions of the reactions of (hydrogen) molecules with surfaces. An international team of researchers, headed by Leiden theoretical chemist Geert-Jan Kroes, published on this subject this week in the journal Science.
Interactions with aerosols boost warming potential of some gases
For decades, climate scientists have worked to identify and measure key substances -- notably greenhouse gases and aerosol particles -- that affect Earth's climate.
Volcanoes played pivotal role in ancient ice age, mass extinction
Researchers here have discovered the pivotal role that volcanoes played in a deadly ice age 450 million years ago. Perhaps ironically, these volcanoes first caused global warming -- by releasing massive amounts of carbon dioxide into the atmosphere. When they stopped erupting, Earth's climate was thrown off balance, and the ice age began.
Transforming Nanowires Into Nano-Tools Using Cation Exchange Reactions
A team of engineers from the University of Pennsylvania has transformed simple nanowires into reconfigurable materials and circuits, demonstrating a novel, self-assembling method for chemically creating nanoscale structures that are not possible to grow or obtain otherwise.
UA scientists discover quantum fingerprints of chaos
Chaotic behavior is the rule, not the exception, in the world we experience through our senses, the world governed by the laws of classical physics.
UT Knoxville and ORNL researchers reveal key to how bacteria clear mercury pollution
Mercury pollution is a persistent problem in the environment. Human activity has lead to increasingly large accumulations of the toxic chemical, especially in waterways, where fish and shellfish tend to act as sponges for the heavy metal.
Novel Chemistry for Ethylene and Tin
New work by chemists at UC Davis shows that ethylene, a gas that is important both as a hormone that controls fruit ripening and as a raw material in industrial chemistry, can bind reversibly to tin atoms.
New nanochemistry technique encases single molecules in microdroplets
Inventing a useful new tool for creating chemical reactions between single molecules, scientists at the National Institute of Standards and Technology (NIST) have employed microfluidics-the manipulation of fluids at the microscopic scale-to make microdroplets that contain single molecules of interest.
More Chemical Reactions Current Events and Chemical Reactions News Articles
 |
Chemical Reaction by The Chemical Brothers Includes Seven Tracks by the Chemical Brothers. |
 |
Chemical Reactions and Chemical Reactors by George W. Roberts (Author) Focused on the undergraduate audience, Chemical Reaction Engineering provides students with complete coverage of the fundamentals, including in-depth coverage of chemical kinetics. By introducing heterogeneous chemistry early in the book, the text gives students the knowledge they need to solve real chemistry and industrial problems. An emphasis on problem-solving and numerical techniques ensures students learn and practice the skills they will need later on, whether for industry or graduate work. |
|
Bill Nye the Science Guy: Chemical Reactions Classroom Edition [Interactive DVD] Starring: Bill Nye the Science Guy Directed By: Erin Gottlieb & James McKenna With more than 16 Emmys® to its credit and legions of fans, it's easy to see why the Bill Nye the Science Guy Series is one of the most popular educational series of all time. Beloved by teachers and students alike, Bill Nye and his unique brand of Way Cool Science make complex science principles accessible for all learners. In Chemical Reactions, have a blast watching the explosive examples Bill Nye uses to explain how everything is made of chemicals. Correlated to National Science Education Standards for grades 4-8, this Classroom Edition DVD includes Public Performance Rights, exclusive interviews with Way Cool Scientists, and printable educator's guide complete with assessment tool. | |
 |
Scientific Explorer's Fizzy Foamy Science Kit of Safe Chemical Reactions by Scientific Explorer Enjoy mixing safe powders to create solutions that foam and fizz. Learn about fun chemistry ideas while developing important science skills. |
 |
Chemical Reaction Agent Orange (Primary Contributor) |
|
Chemical Reaction by The Chemical Brothers Includes Seven Tracks by the Chemical Brothers. | |
|
Hua Xue Fan Ying Gong Cheng Yu Gong Yi = Chemical Reaction E by China Intl Book Trading Corp | |
 |
Chemical Reactions (Reading Essentials in Science - Physical Science) by Jenny Karpelenia (Author) |
 |
SciEd Chemical Reactions Lab Investigation by Neo/Sci Corporation Chemistry Kit, Chemical Reactions Lab Investigation; Series inquiry-based experiments, students discover definition of chemical reaction and understand nature, mechanism, properties, applications in chemistry and biology |
|
Bill Nye the Science Guy Chemical Reactions |
| © 2009 BrightSurf.com |