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Authors
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Lages, S. ; Lindner, P. ; Sinha, P. ; Kiriy, A. ; Stamm, M. ; Huber, K.
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Title
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Formation of Ca2+ -induced intermediate mnecklace structures of polyacrylate chains
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Date
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06.11.2009
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Number
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21644
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Abstract
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Long chain sodium polyacrylate polymers in dilute aqueous solution respond extremely sensitive to the addition of small, stoichiometric amounts of Ca2+ ions. Essential features of this response are a considerable shrinking of the coil dimensions and an additional sensitivity of the coil dimensions toward a change in temperature. To reveal details of this shrinking process, the conformational changes in response to the addition of alkaline earth cations at two different temperatures are investigated by means of light and neutron scattering and by AFM on the same samples, respectively. Partially collapsed coils at 15 °C were further shrunken and modified in shape by increasing the temperature to 30 °C. The scattering curves from the intermediates at 30 °C could successfully be interpreted with a pearl necklace model, which includes a low amount of pearls per polymer separated by 80 nm from each other. AFM investigations of adsorbed chains confirm the drastic conformational changes inferred to the system with the temperature increase by 15 °C. The results are considered to be one of the rare direct evidence for a pearl-necklace-like intermediate along the coil-to-globule transition of polyelectrolyte chains.
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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 42 (2009) 4288-4299
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DOI
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https://doi.org/10.1021/ma8027547
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Tags
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atomic-force microscopy polymer-chain hydrophobic polyelectrolyte light-scattering dna-molecules poor solvents collapse globule transition adsorption
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