Dendrimers amphiphilic

In this section the emphasis will be on assemblies prepared from amphiphilic dendrimers. Amphiphilic dendrimers, carrying both hydrophobic and hydrophilic regions within one molecule, tend to self-assemble into a large variety of different aggregates depending on their structure. The dendritic amphiphiles investigated so far include unimolecular micelles, bolaamphiphiles, superam-phiphiles and various other AB and ABA block copolymers. 

Unimolecular micelles are defined as a class of dendritic macromolecules, wherein an interior hydrophobic core is surrounded by a hydrophilic surface layer. These structures closely resemble the shape of classical micelles (shape, 

Upon immersion in acidic water (pH = 1) these unimolecular inverted micelles form vesicles in which the dendrimer component has a highly distorted conformation with an axial ratio of 1 8 for the highest generations. The amphiphilic dendrimers within the aggregates in solution are thought to have a flattened shape similar to those proposed for dendrimers at the air-water interface (section 16.2.1). 

this observation provided the bridge between the classical surfactants and amphiphilic block copolymers. The versatility of these amphiphiles is based not only on the ability to change the size of the head-group, but also on the possibility of chemically modifying of the dendritic head-group. Carboxylic acid terminated dendritic amphiphiles were prepared that exhibited a pH dependent aggregation behaviour due to the zwitter-ionic nature of their head-groups 

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Roman, C., Amphiphilic dendrimers , Ph.D. thesis, Eindhoven University of Technology (1999). 

High asymmetric induction by amphiphilic dendrimers was reported by Rico-Lattes and co-workers [32]. These water-soluble but THF-insoluble dendrimers (e.g. 22, Scheme 23) consist of useful, readily available chiral auxiliaries and can be used in the homogeneous (when H20 is the solvent) or heterogeneous (in the case of THF as the reaction medium) catalyzed reduction of prochiral aromatic... 

Up to now only amphiphilic dendrimers with soft cores and soft shells were used. Unfortunately the shape and the size of this type of dendrimer also show a dependence on the factors mentioned above [75-77]. By using dendrimers with a hard inner core it would be possible to study the self-organization of amphiphilic dendrimers as related to shape and size of the core. 

Joester D, Losson M, Pugin R et al. (2003) Amphiphilic dendrimers novel self-assembling vectors for efficient gene delivery. Angew Chem Int Ed 42 1486-1490... 

STRUCTURE AND SELF-ASSEMBLY OF AMPHIPHILIC DENDRIMERS IN WATER... 

Figure 11.2 A comparison of the Hartley micellar model with the structure of an amphiphilic dendrimer.

Figure 11.9 (Top) A typical structure of Tha)oimanavan s amphiphilic dendrimers. (Bottom) Schematic representation of micelle-type and inverse miceUe-type structural organization.

Schematic representation of the monolayer organization of amphiphilic dendrimers on the water surface.

Figure 11.16 (Left) Chemical structures of G1 and G3 polyfaryl ether) dendrimers. (Right) Notional depiction of generation-dependent dynamic conformational equilibrium of amphiphilic dendrimers in water interconverting between disklike and spherical morphologies.

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