ABSTRACT
Today, conventional free-radical polymerization (FRP) is still one of the most widely applied processes for the preparation of polymeric materials as nearly 50% of all commercial synthetic polymers are produced by this method. The main reason for this fact is that a wide range of monomers can be polymerized and copolymerized via radical chemistry, which provides a spectrum of materials for various markets. Moreover, the polymerization does not require rigorous process conditions. On the
10.1 Introduction ................................................................................................. 231 10.2 Metal Catalyzed Atom Transfer Radical Polymerization ........................... 232
10.2.1 Initiators......................................................................................... 235 10.2.2 Monomers ...................................................................................... 235 10.2.3 Ligands .......................................................................................... 243 10.2.4 Reverse ATRP ...............................................................................244 10.2.5 Additives ........................................................................................ 253 10.2.6 In Situ Generation of Cu (I) Species via Electron Transfer
Reaction in ATRP..........................................................................254 10.2.7 Catalyst Recovery in ATRP .......................................................... 255
10.3 Nitroxide-Mediated Radical Polymerization (NMP)..................................256 10.4 Reversible Addition-Fragmentation Chain Transfer
Polymerization (RAFT) .............................................................................. 257 10.4.1 RAFT Agents ................................................................................ 283 10.4.2 Synthesis of RAFT Agents ............................................................ 283 10.4.3 Polymerization ............................................................................... 283 10.4.4 Effect of the Structure on the RAFT Agents ................................285 10.4.5 Macromolecular Architectures by RAFT ..................................... 293
10.5 Conclusion ................................................................................................... 293 References .............................................................................................................. 293
other hand, some important elements of the polymerization process that would lead to the well-defined polymers with controlled molecular weight, polydispersity, composition, structural architecture, and functionality are poorly controlled. The importance of the synthesis of polymers with such control has been augmented due to the rising demand for the specialty polymers. Obviously, living polymerization is an essential technique for synthesizing polymers with controlled structures. Moreover, living polymerization techniques allow preparation of macromonomers, macro initiators, functional polymers, block and graft copolymers, and star polymers. In this way, the need for specialty polymers having a desired combination of properties can be fulfilled. Control of complex architectures by living polymerization has largely been achieved using living anionic and cationic as well as group transfer polymerization techniques. From the practical point of view, however, these techniques are less attractive than free-radical polymerization, because the latter can be performed much more easily. Moreover, ionic techniques are limited to a very few vinyl monomers, whereas practically all vinyl monomers can be homo and copolymerized by a free-radical mechanism.
