Dendrimers highly branched

Two new developments are the dendrimers (highly branched, globular, synthetic macromolecules) and modified buckyballs. Together with hydrogels, they are tailored to provide targeted delivery. 

Dendrimers Highly branched polymer of well-defined size and charge (38-40)... 

SPB are mainly prepared by surface-initiated polymerization techniques with improved control of surface coverage, thickness and composition over dendrimers (highly branched macromolecules) or star polymers. They are more stable than directly assembled polymer structures, such as vesicles (polymersomes) and micelles prepared from amphiphilic block copolymers (Cabane et al., 2012). 

The chck approach also served as an efficacious way to synthesize glyco-dendrimers, highly branched nanostructured, monodisperse polymers, which displayed enormous apphcabiUty in many areas, ranging from material science to drug delivery systems and also from biomedicines to catalysis purpose. CuAAC... 

Nonetheless, it was a fairly short step from octopus compounds to dendrimers, and the step was taken by Vogtle in the late 1970s when he attempted to use a cascade reaction to prepare a molecule of the dendrimer type that would now be considered a dendron rather than a fully developed dendrimer. It began with the addition of acrylonitrile to an anfine, followed by reduction of the nitrile to amine. This was followed by a further reaction with acrylonitrile, and the process was repeated several times to yield highly branched macromolecules. There were initially problems with the reduction step but these were overcome, and the preparation of these poly(propylene imine) dendrimers was later commercialized. 

Recently, highly branched macromolecular polyamidoamine dendrimers have been prepared with Co11 bound where the metal ions have additional exchangeable coordination sites.450 These macromolecules show a capacity for catalyzing the hydrolysis of phosphate esters, presumably via intermediate bound phosphoester species. 

As outlined in other chapters in this volume, Tomalia et al. first reported the successful well-characterized synthesis of dendrimers in the early 1980s [1], These molecules range in size from 10 A to 130 A in diameter for generation 0 (GO) through generation 10 (G10). In the ideal situation, PAMAM dendrimers are monodispersed spherical conformation with a highly branched three-dimensional structure (Figure 18.1) that provides a scaffold for the attachment of... 

A majority of the hyperbranched polymers reported in the literature are synthesized via the one-pot condensation reactions of A B monomers. Such one-step polycondensations result in highly branched polymers even though they are not as idealized as the generation-wise constructed dendrimers. The often very tedious synthetic procedures for dendrimers not only result in expensive polymers but also limit their availability. Hyperbranched polymers, on the other hand, are often easy to synthesize on a large scale and often at a reasonable cost, which makes them very interesting for large-scale industrial applications. 

To the best of our knowledge, apart from the above-mentioned systems of Miller and Neenan and the dendrimers presented by our group, no further work on large, highly branched polyphenylene dendrimers has been reported. This chapter will start therefore with the different ways of synthesizing these dendrimers, followed by their functionalization, characterization, and some applications. Finally, we present an outlook describing future work. 

As is also known from dendrimers [18],the properties of highly branched structures depend strongly on the nature of the end groups. Typically a resin, based on HHPA and diisopropanolamine, was functionalized with different mono acids, demonstrating the expected drastic change of the glass transition temperature (Fig. 12). 

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