Publications, controlled radical polymerization

Figure 1 Publication rate of journal papers on radical polymerization and on living, controlled, or mediated radical polymerization for the period 1975-2008 based on SciFinder search (as of March 2010). It does not distinguish forms of controlled radical polymerization. It includes most papers on ATRP, RAFT, and NMP and would also include conventional, non-RDRP, controlled radical polymerizations. It would not include papers, which do not mention the terms living , controlled , or mediated .

Due to the advancements in polymer synthesis there are a number of controlled polymerization techniques available today and, therefore, the number of publications on tailor-made block copolymers has increased especially during the last decade. Besides the living anionic and, to a less extent, also cationic polymerizations various techniques of controlled radical polymerization have become popular. Also some works have been carried out establishing control in polycondensation and even coordination polymerization. Some of the different techniques have been also combined in block copolymer synthesis. Thus an increasing number of monomers have become accessible for the synthesis of tailor-made block copolymers of various chain architectures. 

Figure 1.1 Publication rate of journal papers on radical polymerization and on living, controlled or mediated radical polymerization for period 1975-2002 based on SeiFinder search (as of Mar 2005).

Fig-3. The number of literature publications per year though August/2001 in the general field of controlled/ living radical polymerization (CRP) and those related to specifically to CRP copolymers... 

In a recent publication Okamura et ah (12) describe similar results in a different system. It is believed that the unusual rate increase observed in these various systems which are chemically so different is caused by the physical state of the reaction medium at temperatures a few degrees above Tg. The high viscosity of this gel-like medium presumably favors chain propagation in its competition with termination. This effect, which is kinetically similar to the "gel-effect in free radical polymerizations, can only arise if the termination step (charge recombination) becomes diffusion controlled. The latter process would arise if both ionic species involved in the reaction were of macromolecular size. This is undoubtedly true for the growing chain, but the mobility of the counter ion should only be significantly reduced in such a medium if it is of a polymolecular structure, involving perhaps a voluminous solvation cluster. 

The fifty chapters submitted for publication in the ACS Symposium series could not fit into one volume and therefore we decided to split them into two volumes. In order to balance the size of each volume we did not divide the chapters into volumes related to mechanisms and materials but rather to those related to atom transfer radical polymerization (ATRP) and to other controlled/living radical polymerization methods reversible-addition fragmentation transfer (RAFT) and other degenerative transfer techniques, as well as stable free radical pol5mierizations (SFRP) including nitroxide mediated polymerization (NMP) and organometallic mediated radical polymerization (OMRP). 

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. 

Several publications appeared recently that describe use of controlled/ living radical polymerizations to form block copolymers. Thus, Jerome et al. [435] described formation of block copolymers by using an initiator capable of initiating simultaneously dual living polymerizations ... 

A parallel development was initiated by the first publications from Sawamoto and Matyjaszweski. They reported independently on the transition-metal-catalyzed polymerization of various vinyl monomers (14,15). The technique, which was termed atom transfer radical polymerization (ATRP), uses an activated alkyl halide as initiator, and a transition-metal complex in its lower oxidation state as the catalyst. Similar to the nitroxide-mediated polymerization, ATRP is based on the reversible termination of growing radicals. ATRP was developed as an extension of atom transfer radical addition (ATRA), the so-called Kharasch reaction (16). ATRP turned out to be a versatile technique for the controlled polymerization of styrene derivatives, acrylates, methacrylates, etc. Because of the use of activated alkyl halides as initiators, the introduction of functional endgroups in the polymer chain turned out to be easy (17-22). Although many different transition metals have been used in ATRP, by far the most frequently used metal is copper. Nitrogen-based ligands, eg substituted bipyridines (14), alkyl pyridinimine (Schiff s base) (23), and multidentate tertiary alkyl amines (24), are used to solubilize the metal salt and to adjust its redox potential in order to match the requirements for an ATRP catalyst. In conjunction with copper, the most powerful ligand at present is probably tris[2-(dimethylamino)ethyl)]amine (Mee-TREN) (25). 

Free-radical ring-closure polymerization has been a common phenomenon in polymer chemistry for some time. Inter-intramolecular polymerization dates from the publication of Butler and Angelo in 1957, in which diallyldi-methylammonium bromide was polymerized by a free radical mechanism to produce a soluble polymer with the formation of five-membered rings. Apparently the reaction is kineti-cally controlled since the formation of the five-membered... 

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