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!
What happens in the cell nucleus after fertilization
06.12.2016 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
06.12.2016 | Materials Sciences
06.12.2016 | Medical Engineering
06.12.2016 | Power and Electrical Engineering