Unlike the traditional method for living polymerization, which has been around for more than 50 years, this method takes place at room temperature, uses less metal catalyst to drive the reaction and requires a very short reaction time.
We have basically re-written the equation of how the polymerization process can work, which can have a direct impact on the cost of the reaction and the types of materials that we can create. said Virgil Percec, a professor in Penns Department of Chemistry. Polymerization is a billion-dollar-a-year industry, and the applications for the technology are enormous, ranging from medicine to coatings, from moldable forms of rubber to electronics and even complex organic synthesis, all via these radical reactions.
This new technique, called Single Electron Transfer-Living Radical Polymerization, also offers chemists greater control over the molecular architecture of the polymers they create and allows them to use materials that did not work with the traditional process. The mechanism of the synthesis reaction works so well that there is very little worry about undesirable side reactions, and the resulting polymers do not need to be purified to remove the catalyst. Their findings are presented in the Journal of the American Chemical Society, available online now.
The SET-LRP mechanism can allow for a greater control over the three-dimensional structure of the polymers being created, Percec said. The overall process is not only more efficient, it also provides industrial chemists a new creative tool for building consumer and industrial.
Polymerization links individual molecules, referred to as monomers, together to form synthetic products on a larger-scale. In the chemical reaction to create polymers, chemists use catalysts to decrease the amount of energy it takes to create a shared bond between individual atoms of each monomer. The traditional method, referred to as atom-transfer radical polymerization or metal catalyzed living radical polymerization, demands high temperatures and a great amount of the metal catalyst, in part, because the process depends on the energy it takes to transfer inner-sphere electrons - which are deep within the cloud of electrons surrounding an atom - in the act of bonding monomers together.
The new method created by Percec and his colleagues involves the transfer of outer-sphere electrons, which requires much lower activation energy and, therefore, a different catalytic cycle than atom-transfer radical addition. Both the traditional and SET-LRP processes use copper-based catalysts to drive the reaction, but the SET-LRP reaction uses a common, elemental form of copper - in the form of powder or wire - in the presence of environmentally friendly solvents, such as water, to move the reaction along. This prevents the build up of excess amounts of copper by-products and reduces the need to continually add more catalyst to keep the reaction going.
While this might seem like a refinement of the traditional process - the resulting polymers, in fact, are structurally the same - this method involves an entirely different approach to the chemical reaction, Percec said.
Funding for the research was provided by the National Science Foundation.
Greg Lester | EurekAlert!
Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory
How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy