Divergent dendrimer

Meijer and co-workers also used a divergent dendrimer synthesis to prepare AB diblock structures (Figure 7.13B) in which the polystyrene linear block is used to initiate growth of the polypropylene imine) dendritic block [45], An amino end group had to be introduced in the polystyrene as a core for subsequent growth of the dendritic fragment via an iterative protocol of sequential... 

The development of mass spectroscopic techniques such as matrix assisted laser desorption (MALDI) and electrospray mass spectrometry has allowed the absolute determination of dendrimer perfection [7,8], For divergent dendrimers such as PAMAM and PPI, single flaws in the chemical structure can be measured as a function of generation to genealogically define an unreacted site of or a side reaction producing a loop at a particular generation level. Mass spectromet-ric results on dendrimers, not only demonstrate the extreme sensitivity of the technique, but also demonstrate the uniformity of the molecular mass. The polydispersity index of Mw/Mn for a G6 PAMAM dendrimer can be 1.0006 which is substantially narrower than that of living polymers of the same molecular mass [7],... 

Convergent, supramolecular or more rarely divergent dendrimer assembly using a functional core unit... 

Ligand incorporation was achieved by facile alkoxylation of 4-chloro-substituted ter-pyridine by a hydroxy-terminated carboxylic acid followed by divergent dendrimer con-... 

To obtain polystyrene-poly(propylene imine) block copolymers, the divergent dendrimer synthesis as described in 2.1 was performed onto the PS-CH2-O-CH2-CH2-CH2-NH2 core molecule, with M = 3.2kgmor (based on GPC of PS-CH2-OH). 

Representative divergent dendrimer, bearing four sialosides... 

Gossage, R. A., Munoz-Martinez, E., Frey, H., Burgath, A., Lutz, M., Spek, A. L., Van Koten, G. A novel phenol for use In convergent and divergent dendrimer synthesis access to core functlonallzable trifurcate carbosllane dendrimers-the X-ray crystal structure of [1,3,5-trls 4-(triallylsllyl)phenyl ester benzene]. Chem.- Eur. J. 1999, 5, 2191-2197. 

Figure 18 Schematic representation of divergent dendrimer synthesis (top) and convergent synthesis (bottom). Reproduced from http //en.wikipedia.org/wiki/Dendrimer.

D. Supramolecular Aspects of the Classical Divergent Dendrimer Synthesis... 

Further evidence to support the role of self-assembly in divergent dendrimer synthesis can be found in the construction of poly(amidoamine) PAMAM dendrimers. First, ideality and fidelity of structure is usually a signature of a self-assembly event. This is a universal observation throughout biological systems. In all cases, nearly ideal PAMAM structures are obtained only under mild conditions favoring such organizational events as a prerequisite to bond formation [88]. Attempts to impose more severe reaction conditions (i.e., reaction temperature >40 C) dramatically reduces the ideality of dendrimer structures even in the early generations. Under mild, kinetically favorable reaction conditions however, nearly ideal dendrimer structures are obtained up to the onset... 

A new block type of dendritic polymer has been prepared by Meijer and co-workers [54,55]. Polystyrene-Z>/ocA -dendron (PS-dendr-(COOH) ) was prepared by a divergent dendrimer synthetic methodology using an amine-functionalized polystyrene of well-defined structure as the core for the synthesis of a poly(propylene imine) dendrimer. A representation of the structure is shown in Figure 2. It was reported that the amphiphilic dendrimer exhibited a remarkable generation-dependent aggregation behavior in a variety of salt solutions regardless of pH. 

New divergent dendrimers were prepared by combinations of the previously mentioned functional cores and building blocks. Synthesis of Micel-... 

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