Dendritic structures hydrophobic core

Initial efforts gave rise to well-characterized dendritic macromolecules, but applications remained limited because of the lack of specific functionalities. An exponential increase of publication volume observed for about 15 years testified the growing interest for dendrimers and has led to versatile and powerful iterative methodologies for systematically and expeditiously accessing complex dendritic structures. The perfect control of tridimensional parameters (size, shape, geometry) and the covalent introduction of functionalities in the core, the branches, or the high number extremities, or by physical encapsulation in the microenvironment created by cavities confer such desired properties as solubility, and hydrophilic/hydrophobic balance. Thus, creativity has allowed these structures to become integrated with nearly all contemporary scientific disciplines. 

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,... 

Host-guest systems made from dendritic materials have potential in the areas of membrane transport and drug delivery [68, 84, 85]. In a recent report [136] Tomalia and coworkers investigated structural aspects of a series of PAM AM bolaamphiphiles (e.g., 50) with a hydrophobic diamino do decane core unit. Fluorescence emission of added dye (nile red) was significantly enhanced in an aqueous medium in the presence of 50 unlike the cases when 51 and 52 were added (Fig. 23). Addition of anion surfactants to this mixture generated supramolecular assemblies which enhanced their ability (ca.by 10-fold) to accommodate nile red (53). Further increase in emission was noted by decreasing the pH from the normal value of 11 for PAMAM dendrimers to 7. At lower pH values the... 

Recently, several articles have been published dealing with water soluble dendrimers, due to their outstanding structure and properties which are similar to natural micellar systems, e. g., liposomes. Scheme 17 shows such an example of a dendritic micelle containing a hydrophobic inner core surrounded by a hydrophilic layer of carboxylate groups. The most important difference to natural micelles is that dendritic micelles are covalently bound structures and not dyn-... 

The structure and properties of water soluble dendrimers, such as 46, is, in itself, a very promising area of research due to their similarity with natural micellar systems. As can be seen from the two-dimensional representation of 46 the structure contains a hydrophobic inner core surrounded by a hydrophilic layer of carboxylate groups (Fig. 12). However these dendritic micelles differ from traditional micelles in that they are static, covalently bound structures instead of dynamic associations of individual molecules. A number of studies have exploited this unique feature of dendritic micelles in the design of novel recyclable solubilization and extraction systems that may find great application in the recovery of organic materials from aqueous solutions [84,86-88]. These studies have also shown that dendritic micelles can solubilize hydrophobic molecules in aqueous solution to the same, if not greater, extent than traditional SDS micelles. The advantages of these dendritic micelles are that they do not suffer from a critical micelle concentration and therefore display solvation ability at nanomolar... 

Similar structures can also be prepared using ATRP chemistry and in this case the initiating group is simply a chloromethyl or bromomethyl species at a focal point [204], Linear poly (acrylate) and poly (acrylic acid) blocks [205,206] are then connected to the dendrimer at its core. They were prepared by the copper-catalyzed living radical polymerizations of acrylates with dendrimer-type macroinitiators having a benzyl bromide at the focal point. After hydrolysis, amphiphilic block copolymers with a linear PAA hydrophilic block and a dendritic poly (benzyl ether) as hydrophobic block were obtained [205,206]. 

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