Controlled/living radical main methods

Main Controlled/Living Radical Polymerization Methods. 128... 

Living Radicai Poiymerization. Undoubtedly the main advance in block copolymer synthesis in the last decade has been the development of techniques of living radical polymerization (sometimes termed controlled radical polymerization). The principle of controlled radical polymerization methods is to establish a dynamic equilibrium between a small fraction of growing free radicals and a... 

The tendency of nitrones to react with radicals has been widely used in new synthetic routes to well-defined polymers with low polydispersity. The recent progress in controlled radical polymerization (CRP), mainly nitroxide-mediated polymerization (NMP) (695), is based on the direct transformation of nitrones to nitroxides and alkoxyamines in the polymerization medium (696, 697). In polymer chemistry, NMP has become popular as a method for preparing living polymers (698) under mild, chemoselective conditions with good control over both, the polydispersity and molecular weight. 

Figure 8 Main mechanistic transformation reactions in living and/or controlled polymerization methods. ATRP, atom transfer radical polymerization RAFT, reversible addition-fragmentation chain transfer NMRP, nitroxide-mediated free radical polymerization CROP, cationic ring-opening polymerization AROP, anionic ring-opening poiymerization.

The evolution of the living free-radical polymerization techniques (mainly TEMPO (2,2,6,6-tetramethylpiperidinyl-l-oxy) and ATRP methods) very soon led to the synthesis of macromonomers. These methods combine the advantages of the free-radical polymerization with those of the living polymerization techniques, despite the fact that control over the functionalization reaction is not always comparable to the anionic polymerization methods (91,92). 

Describe the principal criteria that can be used to identify a living polymerization/controlled polymerization (LP/CP). What are the various ways in which living polymerization can be accomplished What are the advantages of living/controlled radical polymerization (LRP/CRP) compared to other methods of LP/CP Describe how the main requirements of LP/CP are ful lied in the following LRP/CRP methods (a) nitroxide mediated polymerization (NMP) or stable free radical polymerization (SFRP), (b) atom transfer radical polymerization (ATRP), and (c) polymerization by reversible addition fragmentation chain transfer (RAFT) ... 

---