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!
An innovative high-performance material: biofibers made from green lacewing silk
20.01.2017 | Fraunhofer-Institut für Angewandte Polymerforschung IAP
Treated carbon pulls radioactive elements from water
20.01.2017 | Rice University
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
20.01.2017 | Awards Funding
20.01.2017 | Materials Sciences
20.01.2017 | Life Sciences