UC Santa Barbara researchers develop a metal-free atom transfer radical polymerization process that uses an organic-based photocatalyst
A team of chemistry and materials science experts from University of California, Santa Barbara and The Dow Chemical Company has created a novel way to overcome one of the major hurdles preventing the widespread use of controlled radical polymerization.
In a global polymer industry valued in the hundreds of billions of dollars, a technique called Atom Transfer Radical Polymerization is emerging as a key process for creating well-defined polymers for a vast range of materials, from adhesives to electronics. However, current ATRP methods by design use metal catalysts, a major roadblock to applications for which metal contamination is an issue, such as materials used for biomedical purposes.
This new method of radical polymerization doesn't involve heavy metal catalysts like copper. Their innovative, metal-free ATRP process uses an organic-based photocatalyst--and light as the stimulus for the highly controlled chemical reaction.
"The grand challenge in ATRP has been: how can we do this without any metals?" said Craig Hawker, Director of the Dow Materials Institute at UC Santa Barbara. "We looked toward developing an organic catalyst that is highly reducing in the excited state, and we found it in an easily prepared catalyst, phenothiazine."
"It's "drop-in" technology for industry," said Javier Read de Alaniz, principal investigator and professor of chemistry and biochemistry at UC Santa Barbara. "People are already used to the same starting materials for ATRP, but now we have the ability to do it without copper." Copper, even at trace levels, is a problem for microelectronics because it acts as a conductor, and for biological applications because of its toxicity to organisms and cells.
Read de Alaniz, Hawker, and postdoctoral research Brett Fors, now with Cornell University, led the study that was initially inspired by a photoreactive Iridium catalyst. Their study was recently detailed in a paper titled "Metal-Free Atom Transfer Radical Polymerization," published in the Journal of the American Chemical Society. The research was made possible by support from Dow, a research partner of the UCSB College of Engineering.
ATRP is already used widely across dozens of major industries, but the new metal-free rapid polymerization process "pushes controlled radical polymerization into new areas and new applications," according to Hawker. "Many processes in use today all start with ATRP. Now this method opens doors for a new class of organic-based photoredox catalysts."
Controlling radical polymerization processes is critical for the synthesis of functional block polymers. As a catalyst, phenothiazine builds block copolymers in a sequential manner, achieving high chain-end fidelity. This translates into a high degree of versatility in polymer structure, as well as an efficient process.
"Our process doesn't need heat. You can do this at room temperature with simple LED lights," said Hawker. "We've had success with a range of vinyl monomers, so this polymerization strategy is useful on many levels."
"The development of living radical processes, such as ATRP, is arguably one of the biggest things to happen in polymer chemistry in the past few decades," he added. "This new discovery will significantly further the whole field."
Melissa Van De Werfhorst | EurekAlert!
Researchers demonstrate existence of new form of electronic matter
15.03.2018 | University of Illinois at Urbana-Champaign
Boron can form a purely honeycomb, graphene-like 2-D structure
15.03.2018 | Science China Press
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...
The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...
At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.
When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...
At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.
Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...
16.03.2018 | Event News
13.03.2018 | Event News
08.03.2018 | Event News
16.03.2018 | Earth Sciences
16.03.2018 | Physics and Astronomy
16.03.2018 | Life Sciences