Poly dendritic molecule

The polydispersity of dendritic molecules, expressed in the form of their poly-dispersity index (PDI), is directly related to their structural perfection. The PDI is a measure of molecular weight distribution. 

Commercially available POPAM and PAMAM dendrimers (see Chapter 4) bearing terminal primary amino groups are currently the most commonly used divergently grown dendrimer structures, followed by poly(benzyl ether) den-drons or poly(benzyl ether) dendrimers (Frechet type) as representatives of con-vergently synthesised dendritic molecules. 

Poly(propylene imine) dendrimers functionalized with hydrophobic alkyl chains (palmitoyl chains or alkyloxyazobenzene chains) assembled into stable monolayers at the air-water interface [122,180]. In the assemblies, the dendrimers adopted a cylindrical amphoteric shape in which the ellipsoidal dendritic moiety acted as a polar head-group and the alkyl chains arranged in a parallel fashion to form an apolar tail (Fig. 33b). This representation is based on the observation that the molecular area of a dendritic molecule increases linearly with the number of end-groups in this molecule. 

Methanofullerene 20 with phenylacetylene dendrimer addends has also been reported [45] (Fig. 10). The UV absorption of fullerodendrimer 20 is particularly strong and is mainly attributed to transitions located on the two dendritic branches of the molecule. The photophysical investigations revealed that the large poly(aryl)acetylene branches act as photon antennae [46]. 

Earlier we found that the addition of alkyl-modified poly(propylene imine) dendrimers to polypropylene leads to fibers which can be dyed in conventional acid or disperse dyeing processes [3]. The alkyl chains make the additive compatible with the polypropylene matrix, while the polar core of the dendrimer can act as a receptor for the dye molecules. This host-guest behavior is analogous to the principle of the dendritic box as described by Meijer et al. [30] and elaborated by Baars et al. for dye extraction processes [31]. 

Kramer and coworkers recently reported on water-soluble dendritic coreshell architectures and studied the influence of the attached carbohydrate shell on the formation and stabilization of metal nanoparticles in water. For this purpose, they used hyperbranched poly(ethylenimine) (PEI) as core molecules and covalently attached different carbohydrates as shells, i.e., glycidol, gluconolactone and lactobionic acid, to obtain the corresponding PEI-glycol, PEI-gluconamide and PEI-lactobionamide. Different molecular weights of PEIX (x = 0.8, 5, 21 or 25 with different Mw = xlO3) were employed [81]. 

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