Patents, controlled radical polymerization

Nitroxide-Mediated Controlled Radical Polymerization (NMCRP) was first discovered by Solomon et al., who patented their discovery in 1985 [205]. This opened up new pathways in the field of free-radical polymerization. Polymer architectures, which were the domain of the anionic polymer chemist, became accessible to the free-radical polymer chemist. However, it was not until the work of Georges et al. [206] was published in 1993, that the world of polymer chemistry became aware of the possibihties of this new class of free-radical polymerization. This was the beginning of what is today one of the leading topics in free-radical polymer chemistry Controlled or Living Free Radical Polymerization. This initiated the search for new Controlled or Living Free Radical Polymerization techniques, and soon afterwards other methods (which will be discussed later) were developed. 

Controlled Radical Polymerization (CRP) is the most recently developed polymerization technology for the preparation of well defined functional materials. Three recently developed CRP processes are based upon forming a dynamic equilibrium between active and dormant species that provides a slower more controlled chain growth than conventional radical polymerization. Nitroxide Mediated Polymerization (NMP), Atom Transfer Radical Polymerization (ATRP) and Reversible Addition Fragmentation Transfer (RAFT) have been developed, and improved, over the past two decades, to provide control over radical polymerization processes. This chapter discusses the patents issued on ATRP initiation procedures, new functional materials prepared by CRP, and discusses recent improvements in all three CRP processes. However the ultimate measure of success for any CRP system is the preparation of conunercially viable products using acceptable economical manufacturing procedures. 

There has been a revolution in free radical polymerization chemistry that began in the 1980s with the seminal patent of Solomon et al. (1986). These scientists found that it was possible to obtain controlled radical polymerization of monomers such a styrene and alkyl (meth) acrylates by effecting free radical polymerization in the presence of stable nitroxyl radicals as shown below. It has been found that these controlled polymerizations carried out... 

Durairaj Baskaran performed doctoral studies at the National Chemical Laboratory, India, and University of Mainz Germany, working jointly with Dr. S. Sivaram and Prof. Axel H. E. Muller. After his PhD (University of Pune, India, 1996), he worked as a senior scientist at the National Chemical Laboratory for several years before joining the University of Tetmessee. His research interests are in the areas of living anionic polymerization and controlled radical polymerization focusing on synthesis and characterization of architecturally controlled polymers, functionalization of carbon nanotubes, nanocomposites, and polymers for energy applications. He has published over 70 research articles and several patents and also coedit i a book. 

Krzysztof Matyjaszewski received his PhD degree in 1976 from the Polish Academy of Sciences under Prof S. Penczek. Since 1985 he has been at Carnegie Mellon University where he is currently ). C. Warner University Professor of Natural Sciences and director of Center for Maaomolecular Engineering. He is also Adjunct Professor at the University of Pittsburgh and at the Polish Academy of Sciences. He is the editor of Progress in Polymer Science and Central European Journal of Chemistry. He has coedited 14 books and coauthored more than 70 book chapters and 700 peer-reviewed publications he holds 41 US and more than 120 international patents. His papers have been cited more than 50000 times. His research interests include controlled/living radical polymerization, catalysis, environmental chemistry, and advanced materials for optoelectronic and biomedical applications. 

A patent was issued to Wertmer and coworkers [271] for controlled radical (co)polymerization of vinyl monomers mediated by nitrones substituted by longer alkyl groups that contained as much as 18 carbon atoms. The nitrone was simply heated in the presence of peroxide and a monomer, such as styrene at 130°C for 24 h. High-molecular-weight polystyrene, = 98,000-146,000 was formed. The ratio of however, was not disclosed... 

A bewildering array of names are used to describe the various controlled/living radial polymerization techniques currently in use. These include stable free radical polymerization (SFRP) [35-38], nitroxide mediated polymerization (NMP) [39], atom transfer radical polymerization (ATRP) [40-42 ] and degenerate transfer processes (DT) which include radical addition-fragmentation transfer (RAFT) [43, 44] and catalyst chain transfer (CCT). These techniques have been used to polymerize many monomers, including styrene (both linear and star polymers) acrylates, dienes, acrylamides, methacrylates, and ethylene oxide. Research activity in this field is currently expanding at a very high rate, as is indicated by the many papers published and patents issued. 

Fr00-Radical Procass. The first commercial PE was developed by Imperial Chemical Industries from 1932 to 1938 using a free-radical process (12). Ethylene was polymerized at high pressure (142 MPa or 1400 atm) and at about 180°C. It was discovered by accident that oxygen impurity could serve as the initiator. An ICI British patent filed in 1936 (13) disclosed pressures of ca 50-300 MPa (500-3000 atm), temperatures of 100-300°C, the necessity of removing heat to control temperature, and the necessity of controlling the oxygen content of the ethylene used. 

Schubert, U.S., Eschbaumer, C.S., Schwaig, C., Andres, P., Kroll, R.M., and Buchmeiser, M.R. Controlled production of polymers, e.g. polystyrene, involves polymerization with radical initiators in the presence of transition metal complex, which is polymerized and fixed on a support such as silica, 2003. German Patent Application DE 100 13 305.3-44 (170300). 

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