Living anionic polymerization applications

Following on from the above, various methods have been described to test and/or rank the livingness of polymerization processes." Ul7 20 All of these tests have limitations.. The following list paraphrases a set of criteria for living polymerization set out by Quirk and Lee11 who also critically assessed their applicability primarily in the context of living anionic polymerization. 

Sequential addition of different monomer charges to a living anionic polymerization system is useful for producing well-defined block copolymers. Thermoplastic elastomers of the triblock type are the most important commercial application. For example, a styrene-isoprene-styrene triblock copolymer is synthesized by the sequence... 

K. Hashimoto, Ring-Opening Polymerization of Lactams. Living Anionic Polymerization and Its Applications , Prog. Polym. Sci. 2000, 25, 1411-1462. 

Fast growing Interest in block copolymers originates from the Intramolecular phase separation, which Is responsible for some unique properties involving many potential applications. In this field again major progress has been accomplished due to the availability of the "living" anionic polymerization techniques. 

Block co-polymers exhibit outstanding potential for a variety of applications as a result of their self-assembly into supramolecular structures (see Section 1.2.4). However, the exploration of organometallic multi-block materials was only begun in the early 1990s. Block co-polymers derived from the living anionic polymerization of vinylferrocene have been already briefly mentioned in Section 12.06.2.2.l.(i). In this section, side-chain metal-containing block co-polymers are surveyed. Examples of block co-polymers with metals in the main chain are discussed in Section 3.X. 

Both the 2,2-diphenyl vinyl and the l-methoxy-l,l-diphenylethyl chain ends are potential endgroups for the anionic polymerization of a variety of monomers by metalation. Our earlier results indicate that quantitative metalation of the 2,2-diphenylvinyl endgroups with alkyllithium cannot be achieved, most likely because of steric hindrance. However, as described recently, the ether cleavage of 1-methoxy-l,l-diphenyl-3,3,5,5-tetramethylhexane or electron transfer to 3,3,5,5-tetra-methyl-l,l-diphenylhex-l-ene by K/Na alloy, Cs or Li led to quantitative metalation resulting in nearly quantitative initiation of the polymerization of methacrylic monomers. Both precursors led to identical (macro)initiators verified by H NMR. These compounds can be considered as models of PIB chain ends formed by LCCP of IB and subsequent end-capping with DPE. The present study deals with the application of this method to the synthesis of different AB and ABA block copolymers by the combination of LCCP and living anionic polymerization. 

Hashimoto, K. 2000. Ring-opening polymerization of lactams. Living anionic polymerization and its applications. Progress in Polymer Science 25(10) 1411-1462. 

The previous example of living, anionic polymerization with very rapid initiation is, admittedly, the simplest application of the method of moments to polymerization problems. While the moment equations could be derived by clever algebra (Eqs. 16.24-16.26), it is often the case that the proper manipulation of summations is not obvious. In this case, it is possible to augment the method of moments with the method of z-transforms. 

For this reason, the focus of this chapter will be on the recent developments (since 2000) in p-star polymers synthesized by the above living anionic polymerization systems, with emphasis on the control of synthetic factors necessary to achieve well-defined structures of p-star polymers, that is, molecular weight, molecular-weight distribution, arm number, and composition. In the last 20 years, rapid progress in living/controlled radical polymerization systems as well as the application of click makes possible the synthesis of several new p-star polymers. Therefore, representative examples will also be described. The syntheses of p-star polymers before 2000 are beyond the scope of this chapter, although they will be briefly described in Section 4.2, since such subjects have been covered elsewhere by several excellent reviews (Hadjichristidis, 1999 Hadjichristidis et al, 2001). 

Poly(31) has attracted considerable attention over the years because of practical biomedical applications such as contact lenses, coating of surgical sutures, hydrogels, and hemodialysis membranes. The success of the living anionic polymerization of protected monomers, 3 la-3 Id, opens the way to newly design well-defined amphiphilic block copolymers with more potential applications. A series of block copolymers of 31a with styrene, a-methylstyrene, 4-octylstyrene, or isoprene were synthesized and their surface structures and environmental movements were characterized in detail by TEM, X-ray photoelectron spectroscopy (XPS), and contact angle measurements. The surface reconstruction was clearly observed... 

Durairaj Baskaran performed doctoral studies at the National Chemical Laboratory, India, and University of Mainz Germany, working jointly with Dr. S. Sivaram and Prof. Axel H. E. Muller. After his PhD (University of Pune, India, 1996), he worked as a senior scientist at the National Chemical Laboratory for several years before joining the University of Tetmessee. His research interests are in the areas of living anionic polymerization and controlled radical polymerization focusing on synthesis and characterization of architecturally controlled polymers, functionalization of carbon nanotubes, nanocomposites, and polymers for energy applications. He has published over 70 research articles and several patents and also coedit i a book. 

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