Controlled radical polymerization anionic

The controlled radical polymerization techniques opened up a new era in polymer synthesis, and further growth and developments are certain. However, the control of the molecular characteristics and the variety of macro-molecular architectures reported by these methods cannot be compared with those obtained by other living polymerization techniques such as anionic polymerization. 

In contrast to the above polymerizations via anionic and/or coordination anionic mechanisms, radical polymerization initiated with metalloporphyrins remains to be studied. The only example of controlled radical polymerization by metalloporphyrins has been reported by Wayland et al. where the living radical polymerization of acrylic esters initiated with cobalt porphyrins was demonstrated. In this section the radical polymerization of MMA initiated with tin porphyrin is discussed. 

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. 

Since the discovery of living polymerizations by Swarc in 1956 [1], the area of synthesis and application of well-defined polymer structures has been developed. The livingness of a polymerization is defined as the absence of termination and transfer reactions during the course of the polymerization. If there is also fast initiation and chain-end fidelity, which are prerequisites for the so-called controlled polymerization, well-defined polymers are obtained that have a narrow molar mass distribution as well as defined end groups. Such well-defined polymers can be prepared by various types of living and controlled polymerization techniques, including anionic polymerization [2], controlled radical polymerization [3-5], and cationic polymerization [6, 7]. 

TABLE 3.1 Differences and Common Features of Living Anionic and Controlled Radical Polymerization Processes (Kinetic Constants According to Fig. 3.4)... 

Most of the cases discussed above are related to the use of polystyrene, but surface segregation is a universal phenomenon and can be transposed to other systems. Table 5.3 reports a non-exhaustive list of binary blends in which segregation occurred and in which the surfaces were decorated with functional groups. End-functional fluoro polymers are commonly developed via different chemistries (ring opening, controlled radical or anionic polymerization) and used as surface... 

Each strategy involves various polymerization techniques, such as conventional and controlled radical polymerizations (CRPs), anionic polymerization, ring-opening metathesis polymerization (ROMP), and cationic polymerization. A judicious combination of a synthetic strategy and a polymerization technique can facilitate the preferential control of certain structural parameters, and this demonstrates distinct advantages with respect to the molecular design, as well as... 

Transformations Involving Anionic and Controlled Radical Polymerization... 

Currently, ATRP is the most widely used controlled radical polymerization in anion-to-radical transformation methodology. The first such example was reported by Acar and Matyjaszewski [61], and utilized for the preparation of AB- and ABA-type block copolymers. The macroinitiators, PSt and polyisoprene-b-polystyrene (PIP-fc-PSt) containing 2-bromoisobutyryl end groups were prepared by living anionic polymerization and a suitable termination agent. These polymers were then used as macroinitiators for ATRP to prepare block copolymers with methyl acrylate (PSt-b-PMA), butyl acrylate (PSt-b-PBA), methyl... 

The transformation reaction may be also possible by using an opposite strategy, from a controlled radical polymerization to a living anionic polymerization. The most widely applied controlled radical polymerization for this particular transformation is ATRP, due mainly to the fact that hydroxyl and amino groups, which are potential initiating sites for the AROP of certain monomers, are compatible with the ATRP of vinyl monomers. Examples of such transformations have been summarized recently [62, 63], while the general concept is shown in Scheme 11.15, based on an example of the combination ATRP of vinyl monomers with the AROP of lactides [71]. 

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