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Authors
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Klos, J. S.; Paturej, J.
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Title
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Complexation between Dendritic Polyelectrolytes and Amphiphilic Surfactants: The Impact of Surfactant Concentration and Hydrophobicity
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Date
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11.07.2023
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Number
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0
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Abstract
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The solution structure of complexes composed of the cationic dendrimer, anionic surfactants, and their counterions is studied by molecular dynamics simulations using the bead–spring coarse-grained model. We identify that depending on the surfactant concentration and hydrophobicity the system exists in three structural regimes. In the first regime surfactant molecules are noncooperatively absorbed by the dendrimer. Here, the pervaded volume of the dendrimer and the bulk solution contain loosely distributed unimeric surfactants and counterions. In the second regime hydrophobic attractions between surfactant tails give rise to cooperative binding. The absorbed surfactants self-assembly into multichain micellar-like aggregates, whereas the bulk solution consists of separate unimers. In the third regime the surfactants form multichain aggregates both within the interior of the dendrimer and in the bulk. Our data indicate that self-assembly of the absorbed surfactants affects the dendrimer conformations as compared to its neutral counterpart. In the case of noncooperative binding the dendritic polyelectrolyte swells due to the osmotic pressure exerted by the absorbed unimers and counterions. In the regimes characterized by cooperative binding and pronounced self-aggregation of the encapsulated surfactants swelling of the dendrimer is suppressed. This is attributed to a reduction of the osmotic pressure inside the macromolecule due to the ion exchange phenomenon appearing as a result of strong Coulomb attractions between charged monomers of the dendrimer and the encapsulated micellar aggregates. We also find that aggregate formation affects the overall charge accumulated in the dendrimer. In particular, for the dendrimer loaded with massive aggregates, we report the charge inversion effect which transforms the cationic dendrimer into an anionic dendrimer–surfactant complex. Our results provide molecular insights into self-assembly of supramolecular complexes and controlled absorption of guest surfactant molecules in dendrimer-based host–guest systems.
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Publisher
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Macromolecules
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Wikidata
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Citation
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Macromolecules 56 (2023) 5022-5032
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DOI
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https://doi.org/10.1021/acs.macromol.3c00223
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Tags
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