Presidential Green Chemistry Challenge: 2009 Academic Award
Professor Krzysztof Matyjaszewski of Carnegie Mellon University
Atom Transfer Radical Polymerization: Low-impact Polymerization Using a Copper Catalyst and Environmentally Friendly Reducing Agents
Innovation and Benefits: Hazardous chemicals are often required in the manufacture of important polymers such as lubricants, adhesives, and coatings. Professor Matyjaszewski developed an alternative process called "Atom Transfer Radical Polymerization (ATRP)" for manufacturing polymers. The process uses chemicals that are environmentally friendly, such as ascorbic acid (vitamin C) as a reducing agent, and requires less catalyst. ATRP has been licensed to manufacturers throughout the world, reducing risks from hazardous chemicals.
Summary of Technology: Worldwide production of synthetic polymers is approximately 400 billion pounds per year; approximately half of this involves free radical polymerization. With the recent development of controlled radical polymerization (CRP), it is now possible to make well-defined polymers with precisely controlled molecular structures. Atom transfer radical polymerization (ATRP) is one such technology; it is a transition-metal-mediated, controlled polymerization process that was discovered at Carnegie Mellon University (CMU) in 1995. Since then, Professor Matyjaszewski and his group have published over 500 scientific papers on CRP; these papers have been cited over 30,000 times, making Professor Matyjaszewski the second-most cited researcher in all fields of chemistry in 2008. This explosive interest in ATRP is due to its simplicity and ability to tailor-make functional macromolecules for specialty applications. ATRP has become the most versatile and robust of the CRP methods.
Professor Matyjaszewski has been working continually to increase the environmental friendliness of his process. During the last four years, he and his team at CMU have developed new catalytic systems that dramatically decrease the concentration of transition metal, while preserving good control over polymerization and polymer architecture. The latest improvements are activators generated by electron transfer (AGET, 2004), activators regenerated by electron transfer (ARGET, 2005), and initiators for continuous activator regeneration (ICAR, 2006).These methods allow the preparation, storage, and use of the most active ATRP catalysts in their oxidatively stable state as well as their direct use under standard industrial conditions. The recent discovery of ARGET ATRP reduces the amount of copper catalyst from over 1,000 ppm to around 1 ppm in the presence of environmentally friendly reducing agents such as amines, sugars, or ascorbic acid. AGET and ARGET ATRP provide routes to pure block copolymers. The new processes allow oxidatively stable catalyst precursors to be used in aqueous homogeneous, dispersed (miniemulsion, inverse miniemulsion, microemulsion, emulsion, and suspension), and solventless bulk polymerizations. Professor Matyjaszewski's work is opening new "green" routes for producing many advanced polymeric materials.
ATRP has become an industrially important means to produce polymers. Since 2003, ATRP has been licensed to 8 of the over 40 corporations funding the research at CMU (PPG, Dionex, Ciba, Kaneka, Mitsubishi, WEP, ATRP Solutions, and Encapson). Licensees around the world have begun commercial production of high-performance, less-hazardous, safer materials including sealants, coatings, adhesives, lubricants, additives, pigment dispersants, and materials for electronic, biomedical, health, and beauty applications.
Podcast on the technology:
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