Polyester dendritic

Padilla De Jesus OL et al (2002) Polyester dendritic systems for drug delivery applications in vitro and in vivo evaluation. Bioconjug Chem 13 453—461... 

Ihre, H.R., Padilla De Jesus, O.L., Szoka, F.C. Jr., Frechet, J.M. Polyester dendritic systems for drug delivery applications Design, synthesis, and characterization. Bioconjug. Chem. 2002,13 (3), 443-452. 

Padilla De Jesus, O. L., Ihre, H. R., Gagne, L., Frechet, J. M., and Szoka, F. C., Jr. 2002. Polyester dendritic systems for drug delivery applications In vitro and in vivo evaluation. Bioconjug Chem 13(3), 453-461. 

Due to dieir compact, branched structure and to die resulting lack of chain entanglement, dendritic polymers exhibit much lower melt and solution viscosity dian their lineal" counterparts. Low a-values in die Mark-Houwink-Sakurada intrinsic viscosity-molar mass equation have been reported for hyperbranched polyesters.198 199 Dendrimers do not obey diis equation, a maximum being observed in die corresponding log-log viscosity-molar mass curves.200 The lack of chain entanglements, which are responsible for most of the polymer mechanical properties, also explains why hyperbranched polymers cannot be used as diermoplastics for structural applications. Aldiough some crystalline or liquid... 

Macromolecules dendritic, 285 hyperbranched, 284-286 Main-chain liquid crystalline polymers, 49 Main-chain polyester LCP mesogenic units, 50... 

The presence of a large number of chain-ends in the fully synthesized dendrimer molecules makes them highly soluble and also readily miscible, for example with other dendrimer solutions. The solubility is controlled by the nature of the end-groups, so that dendrimers with hydrophilic groups, such as hydroxyl or carboxylic acid, at the ends of the branches are soluble in polar solvents, whereas dendrimers with hydrophobic end-groups are soluble in non-polar solvents. The density of the end-groups at the surface of the dendrimer molecule means that they have proportionately more influence on the solubility than in linear polymers. Hence a dendritic polyester has been shown to be more soluble in tetrahydrofuran than an equivalent linear polyester. 

H. Ihre, A. Hult, J. M. J. Frechet, and I. Gitsov, Double-stage convergent approach for the synthesis of functionalized dendritic aliphatic polyesters based on 2,2-bis(hydroxymethyl)propionic acid, Macromolecules, 31 (1998) 4061 1068. 

Amongst the first studies presenting the use of dendritic polymers for thermoset applications was the work of Hult et al. [62]. They modified hyperbranched hydroxy functional polyesters with various ratios of maleate-allyl ether/alkyl ester end groups. Dependent on this ratio, resins with different vis-... 

A wide range of other monomer units have been employed in the synthesis of hyperbranched macromolecules and the range of structures obtained is nearly as diverse as those for dendritic macromolecules. For example, hyperbranched polyphenylenes [93], polyesters [104, 107-109], polyethers [110-112], polyamides [113], polysilanes [114], polyetherketones [100], polycarbazoles [115], etc. [116-118] have been prepared. Interestingly, a number of groups have also used growth processes other than condensation chemistry to prepare hyper-... 

The first part of this review deals with the synthesis and characterization of dendritic aliphatic polyesters based on 2,2-bis(dimethylol)propionic acid (bis-MPA) and 1,1,1 -tris(hydroxyphenyl)ethane (THPE), as core molecule. The convergent growth approach described earlier was applied. We also present H NMR self-diffusion studies of dendrimers of first, second, and third generation. 

The chosen ABj monomer for the synthesis of die dendritic aliphatic polyesters Dl, D2, and D3 was bis-MPA. In the convergent growth approach, dendrons of certain generations were initially synthesized. In a final step these dendrons were coupled to the polyfunctional core molecule (see Scheme 2). To get an acceptable overall yield it is important that all reactions such as coupling, protection, and deprotection are selective and proceed in high yields since a laige number of steps are involved in the synthesis of the final dendrimers. 

Since no adequate SEC standards were available, linear polystyrene was used as standard. As expected, the determined molar masses were not in agreement with the theoretical molar masses. This could be explained by the differences in hydro-dynamic volume between linear polystyrene standards and the dendritic polyesters. SEC analyses showed polydispersity values (A/ /M ) below 1.02 for dendrimers Dl, D2, and D3, which was the maximum resolution of the column (Table 2, Figure 4). 

Table 2. SEC Measurements of Dendritic Polyesters of First, Second, and Third Generation (D1, D2, and D3)...

In recent years cationic dendritic structures such as carbosilane-based [215], triazine-based [216], polyester [217] and amphiphilic dendrimers [218] have been investigated for transfection purposes with promising results, thus offering novel alternatives to the exploration of dendrimer-based nucleic acid delivery. 

These features of these materials spurred the scientific community to utilize them in biomedical applications [49]. In particular, the synergy between their multivalency and size on the nanoscale enables a chemical smartness along their molecular scaffold that achieves environmentally sensitive modalities. These functional materials are expected to revolutionize the existing therapeutic practice. Dendritic molecules, such as polyamidoamine, polylysine, polyester, polyglycerol (PG), and triazine dendrimers, have been introduced for biomedical applications to amplify or multiply molecularly pathopharmacological effects [73]. 

Dendritic polymers are used as functional thin layers. Highly branched aromatic polyesters with polar end groups show good response behaviour in gas phase and liquid sensors [46]. Ease of recycling of the expensive platinum complexes (e.g. by nanofiltration) is a positive aspect of the use of such sensor den-drimers [47]. 

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