Location of the Terminal Groups

To distinguish the terminal groups from the groups of the earlier generations, 

but not all of the terminal units are near the outside of the dendrimer at any given time. The SAXS studies [17] of the segment density distribution have shown that there is an abrupt transition region at the outside of large PAM AM dendrimers. The combination of these two factors suggests that the terminal functionalities of dendrimers are accessible from the outside and available for chemical reactions such as attachment to surfaces, mounting of a catalyst, or for use as a crosslink junction. 

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Very recently, Topp et al. [29] probed the location of the terminal groups of a dendrimer of seventh generation using SANS. These authors concluded that the terminal units as well as nearly half of its monomer units are located in the vicinity of the surface of the molecule. This is in contradiction to the results derived from simulations (see Sect. 2). In addition, it is difficult to reconcile this result with the findings of [23,24] which showed that flexible dendrimers have the maximum density at the center of the molecule. 

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