Dendrimers rheological properties

Compared to dilute solution viscometry and to some extent to bulk rheology, the flow properties of dendrimers in concentrated solutions have been the least investigated area of dendrimer rheology. In fact, with the notable exception of some recent data on generation 4 PPI in water [22] the only [32] reported... 

A paper on The rheological properties of poly(fluorophenylene germane) dendrimers was published by Myasnikova and co-workers in the Russian journal Polym. Sci., Ser. 

Like many polymers, the fluidity or flow (rheological) properties of denrimers are of interest (Box 14.1). Dendrimers behave like soft, spherical particles, surrounded by a hard surface shell and hence are often described as core-shell type bodies. Hence the interior of dendrimers can be deformed according to the type of linkage and building blocks and my contain voids suitable for encapsulating guest species.2... 

Hyper-branched aliphatic polyesters are different from linear polyesters because of their unique mechanical and rheological properties, which can easily be tailored by changing the nature of the end group [156-159]. Both dendrimers and hyper-branched macromolecules are prepared from AB2 monomers, using dif-... 

In solution, dendrimers form close-packed, globular, or spherical shapes when the molecular weight is high enough, unlike the expanded flexible coil structures of linear polymers. This has a significant effect on the rheological properties, e.g., the... 

The monodispersity, the large number of surface functionalities, and the unique rheological properties make dendrimers and hyperbranched polymers potential candidates for a variety of applications such as biosensing [249], catalysis [250], gene therapy [251], and lubricant viscosity-index (VI), just to name a few. However, the mechanochemistry of dendrimers and hyperbranched polymers remains little understood. 

Theoretical description of dendritic structures is an active but difficult topic because the length between branched points is close to or even smaller than the Kuhn length, above which the segments can be thought of as if they are freely jointed with each other. Most modeling or simulation work has focused on the quasi-static and rheological properties of hyperbranched polymers and dendrimers in shear flow [240, 244, 255-263]. Limited amounts of data were published for dendrimers and hyperbranched polymers within elongational flow field. 

Research on the bulk rheological properties of dendrimers is still hampered due to the restrictive quantities necessary for these investigations since dendrimer synthesis is conducted mainly on the milligram scale, and the few commerdal products are very costly to obtain for these studies. In addition, the dendrimers must possess suffident thermal stability and care must be taken to avoid thermal oxidation as well as moisture absorption for more polar dendrimers. 

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