Hyperbranched chain-growth approaches

Many methods have been reported to synthesize hyperbranched polymers. These materials were first reported in the late 1980s and early 1990s by Odian and Tomalia [9], Kim and Webster [10], and Hawker and Frechet [11]. As early as 1952, Hory actually developed a model for the polymerization of AB -type monomers and the branched structures that would result, identified as random AB polycondensates [46], Condensation step-growth polymerization is likely the most commonly used approach however, it is not the only method reported for the synthesis of statistically branched dendritic polymers chain growth and ringopening polymerization methods have also been applied. 

As for step-growth-based polymerization methods. Fig. 1.3 shows two typical approaches in the preparation of hyperbranched chains (A) co-polycondensation [49-56] and (B) self-polycondensation [1, 23, 30-32, 40-48]. The co-polycondensation... 

The versatility of polymerization resides not only in the different types of polymerization reactions and types of reactants that can be polymerized, but also in variations allowed by step-growth synthesis, copolymerization, and stereospecific polymerization. Chain polymerization is the most important kind of copolymerization process and is considered separately in Chapter 7, while Chapter 9 describes the stereochemistry of polymerization with emphasis on the synthesis of polymers with stereoregular structures by the appropriate choice of polymerization conditions, including the more recent metallocene-based Ziegler-Natta systems. Synthetic approaches to starburst and hyperbranched polymers which promise to open up new applications in the future are considered in an earlier chapter dealing with step-growth polymerization. 

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