Stable free radical polymerization advantages

Over the past few years there has been a tremendous interest in living radical polymerizations. One type of living radical polymerization is stable free radical polymerization, SFRP, where a stable free radical such as TEMPO (2,2,6,6-tetramethylpiperidinoxyl) is used to reversibly cap the growing polymer chain (L2). SFRP has the advantage over conventional radical polymerization in that the polymers prepared are living and can be used for further polymerization to make blocks or other complex architectures. The polymers prepared by the SFRP process have a narrower molecular weight distribution compared to polymers prepared by conventional radical polymerization in the case of block copolymers this may be a desirable attribute. This article focuses on the use of the SFRP process to prepare random copolymers. 

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) ... 

Microemulsion polymerisation has shown a great advantage over conventional polymerisation strategies such as emulsion polymerisation with respect to the end particle size, polydispersity and reproducibility of the product characteristics. Although we still face severe problems regarding the polymerisation of microemulsions (see Section 11.2 in Chapter 11), it has been employed for the synthesis of polymeric nanoparticles of pharmaceutical interest. Microemulsion polymerisation involves free-radical polymerisation in a large number of monomer-swollen microemulsion droplets and represents a thermodynamically stable, transparent one-phase reaction system. Generally, the microemulsion droplet is considered as initiation locus for the polymerisation. The type of microemulsion used for the polymerisation depends on the monomer properties [148]. 

The process of phase transfer free radical pol)mierization extends the use of typically organic insoluble free radical initiators into solution and bulk processes, whereas previously they could only be used in water based systems such as in emulsion polymerizations This is advantageous since the Initiators in question are generally more stable and therefore present fewer storage and handling problems as opposed to typical organic-soluble initiators, many of which require refrigeration, etc. 

NMP was originally initiated by a bicomponent pathway, comprising a classical thermal initiator, such as 2,2 -azobisisobutyronitrile (AIBN) or benzoyl peroxide (BPO), in combination with 2,2,6,6-tetramethylpiperidinyl-l-oxy (TEMPO, Table 1, 1) as the stable free nitroxide. This system has the advantage of using classical radical polymerization processes with the only addition of free nitroxide. This initiating system can be also highly desirable from both the economic and practical points of view. 

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