Dendritic polyamine architectures with lipophilic shells as nanocompartments for polar guest molecules: A comparative study of their transport behavior

Abstract

Dendritic core‐shell architectures were synthesized by simple melt reactions of polyethylenimine (PEI) with different fatty acids. These systems were investigated towards their ability to encapsulate various guest molecules. Parameters, such as the length of the attached alkyl chain, size of the polymer core, concentration of the core‐shell architecture in solution, pH, and nature of the guest molecule were investigated and compared. Guest molecules that bear anionic groups, such as carboxylate, phosphate, sulfonate, or acidic OH groups, as present in phenol units, are readily encapsulated and transferred from the aqueous phase to the organic phase because of multiple anionic–cationic interactions. Hyperbranched polymer architectures exhibit enhanced encapsulation properties when compared with their linear counterparts. In case of the hyperbranched system PEI25C16 amide higher transport capacities were observed at lower concentrations of the polymer, for example, 26 guest molecules at 10−5 mol L−1 versus 143 at 10−6 mol L−1, suggesting formation of larger aggregates. The aggregation behavior of these polar nanocompartments were investigated at different concentrations by AFM showing particle aggregates of typically 250 nm at a concentration of 10−5 M. The individual particle sizes in these aggregates are similar to the particle size at 10−6 M concentration, typically 4.0–5.5 nm (AFM height). This indicates that aggregate formation takes place at concentrations higher than 10−8 M and transport might be mediated by small aggregates rather than unimolecular particles. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2287–2303, 2007

Structure‐Transport Relationship of Dendritic Core‐Shell Nanocarriers for Polar Dyes

“…We have also reported on a similar aggregates formation among stable core-shell architectures. [10,11] However, the critical aggregation concentrations (CACs) are strongly dependent on the length of PEG shells. For the N1 system which has a PEG chain with 4 EG units, a CAC of 4.0 Â 10 À5 M was obtained.…”

“…During the last decade, the dendritic core-shell architectures have been considered as unimolecular systems during the encapsulation of guest molecules. [10][11][12][13] In the past, we have observed that shell functionalized hyperbranched polyamines can also encapsulate polar guest molecules and transport them to a nonpolar organic media, such as chloroform from aqueous media. [8,9] Further research confirmed that the formation of aggregates among dendritic core-shell architectures played a predominant role in the encapsulation process.…”

“…[8,9] Further research confirmed that the formation of aggregates among dendritic core-shell architectures played a predominant role in the encapsulation process. [10,11] The encapsulation occurred only when the core-shell architectures self-assembled into supramolecular aggregates above a well-defined threshold concentration.…”

A novel vegetable oil–lactate hybrid monomer for synthesis of high‐Tg polyurethanes

“…[1][2][3][4][5][6][7] In recent years, a variety of polymeric materials have been developed and tested with plant oils as feedstocks. Among other products, plant oil-based polyurethanes (PUs) are the most extensively studied attributing to their simple preparation yet greatly promising applications.…”

Selective Encapsulation of Ionic Dyes by Core/Shell Amphiphilic Macromolecules Derived from Hyperbranched Polyethylenimine: Properties through Structures

“…[1][2][3][4][5][6][7][8][9][10][11] This property is related to the roughly defined structure of the hyperbranched core. On the other hand, highly specific molecular recognition is realized almost exclusively by a specific host/guest interactions such as hydrogen bonding, metal/ligand interaction, topological trapping, or their appropriate combinations.…”