Hyperbranched Molecular Nanocapsules:  Comparison of the Hyperbranched Architecture with the Perfect Linear Analogue

Abstract

The results of a comparative study of hyperbranched, partially esterified polyglycerols with their linear polyglycerol analogues with respect to molecular encapsulation and phase transfer are reported. Two hyperbranched polyglycerol samples with molecular weights of 3000 and 8000 g/mol (Mw/Mn = 1.3), respectively, have been partially esterified using palmitoyl chloride. The same modification was applied to the structurally analogous linear polyglycerol (3000 g/mol). A detailed UV-vis study correlated with viscosity experiments demonstrated that only the hyperbranched core-shell structures form "nanocapsules", leading to the encapsulation of polar guest molecules. The results underline the crucial role of the hyperbranched topology and the resulting solution conformation for supramolecular guest encapsulation and phase transfer. The unusually compact ("collapsed") structure assumed by the hyperbranched core-shell amphiphiles in apolar media is responsible for the formation of a hydrophilic compartment, capable of irreversibly taking up guest molecules.

Hyperbranched Polymers: Structure of Hyperbranched Polyglycerol and Amphiphilic Poly(glycerol ester)s in Dilute Aqueous and Nonaqueous Solution

“…13,14 A partial esterification of hyperbranched polyglycerols using fatty acid chlorides provided the amphiphilic polyglycerols that quantitatively extract various dyes from the aqueous phase into apolar media, stabilize nanosize palladium colloids, [15][16][17][18] and are able to extract catalytically active polar pincer Pt(II) complexes. 19,20 The intriguing phase transfer properties of hyperbranched polyglycerol nanocapsules have been explained by their hydrophobic shell/hydrophilic core structure.…”

Synergistic assembly of hyperbranched polyethylenimine and fatty acids leading to unusual supramolecular nanocapsules

“…Hyperbranched polyols prepared in a onestep process, esterified with fatty acid chlorides in a second step, display an amphiphilic core-shell structure. 7 They have been successfully used to extract and irreversibly encapsulate various polar dyes from the aqueous phase. Surprisingly, all dendrimer-based core-shell architectures for phase transfer processes have been obtained via covalent linking of hydrophobic alkyl chains to the polyfunctional core, followed by several purification steps.…”

Hyperbranched 5,6-glucan as reducing sugar ball

“…Thus, various types of dendrimers, star polymers, and hyperbranched polymers have been synthesized and their properties were compared to the linear analogues. 23,[33][34][35][36][37][38][39][40][41][42][43][44][45][46] easily than glycodendrimers and star-shaped glycopolymers. [71][72][73][74][75][76] Recently, we proposed that the ringopening multibranching polymerization of anhydro and dianhydro sugars as latent AB m -type monomers should be a convenient method of synthesizing hyperbranched glycopolymers with a novel spherical macromolecular architecture, [77][78][79][80][81][82][83] for example, the hyperbranched polysaccharides from the cationic polymerization of 1,6-anhydro--D-hexopyranose, the hyperbranched poly(2,5-anhydro-D-glucitol) from 1,2:5,6-dianhydro-D-mannitol, and the hyperbranched polytetritols of 1,4-anhydrotetritol and 2,3-anhydrotetritol.…”