Patents, controlled radical

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... 

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... 

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. 

While it has been less generally recognized, there are free radical reaction systems in which hydrogen atom transfer between radicals is not rate controlling but does control the selectivity with which the various possible reaction products are formed. This chapter is a study of the effect of HCl on such a reaction system, the thermal alkylation of ethylene. (The effect of HCl upon this reaction was first disclosed in one of the authors patents (4). Several years after this disclosure, Schmerling (6) published a paper which, though differing in many details, showed... 

In Amoco patents [18b], the addition of controlled amounts of water after the initiation ofthe oxidation reaction is claimed to be a tool to obtain a better yield to AA. The best yield achieved was 88% (based on the identifiable compounds) at 98% cyclohexane conversion, with a Co(II) acetate catalyst, an acetic add solvent, at 95 °C and 70 atm air pressure. It is reported that water, if present during the induction period, depletes the concentration of free radicals in the absence of water, the yield was remarkably lower. These results are comparable to those attained by the air /nitric acid two-step oxidation of cydohexane. 

The patent describing this development discloses that a mixture of a thermally stable phenolic antioxidant and a sterically hindered phosphite was used in a hydrotreated base stock. However, the heterosynergism between the radical scavenger (phenolic antioxidant) and the hydroperoxide decomposer (phosphite) was not shown in solvent-refined base stocks. An additional benefit of this technology is energy saving, due to extremely good control of viscosity. 

During the last fifteen years an explosive increase has been observed in the number of publications on CRP, including a dramatic increase in the nrrmber of patent applications and several symposia devoted partially, or entirely, to CRP." " Figure 1 illustrates resrrlts of a recent SciFinder Scholar search using the following terms controlled radicalpolymn or living radical polymn... 

His research interests have included almost all aspects of water-soluble polymers kinetics and synthesis by free-radical processes, controlled substituent placement in the derivati-zation of carbohydrate polymers, solution and interfacial adsorption and viscosity behavior of both polymer types, and meaningful extrapolation of such fundamental data to the performance of water-soluble polymers in application formulations. He has published more than 70 technical papers and received several patents in these areas of study. 

The sheer size and value of the polyethylene industry ensure that there is continued research, progress, and development in catalysis, for their potential commercial impact. Although this whole subject is not within the scope of this chapter, we mention a couple of aspects of the progress, which offer the potential to impact this industry. In 1995, DuPont introduced work, carried out with them at the University of North Carolina—via the largest patent applicafion ever in the USA. They disclosed what are described as post-metallocene catalysts. These are transition and late transition metal complexes with di-imine ligands, which form part of the DuPont Versipol technology. Such catalysts create highly branched to exceptionally linear ethylene homopolymers and linear alpha-olefins. Late transition metals offer not only the potential for the incorporation of polar comonomers, which until now has only been possible in LDPE reactors, but also their controlled sequence distribution, compared to the random composition of free radical LDPE copolymers. Such copolymers account for over 1 million tons per annum [20]. Versipol has so far only been cross-licensed and used commercially by DuPont Dow Elastomers (a former joint venture, now dissolved) in an EPDM plant. 

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. 

Whereas the reactivity of a bleach system can be controlled by its concentration, selectivity is an intrinsic property. To suppress dye damage, a number of patents claim the use of agents able to interfere with the reactive bleach intermediates such as radicals or singlet oxygen [75]. In most cases, however, their effect is only minimal or dye-specific [76,77]. 

Solomon, D.H., Rizzardo, E., and Cacioli, P. (1985) Substd. alkyl-amine cpds.— useful as controlled growth free radical polymerisation initiators for unsaturated monomers. Patent Number EP135280-A2. 

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