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Authors
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Petzold, G. ; Steinbach, C. ; Loos, A. ; Schwarz, S.
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Title
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Characterization of weak polyelectrolytes in aqueous solution - charge and isoelectric point in dependence on the molecule structure
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Date
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19.05.2017
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Number
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52526
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Abstract
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The topic of this work was the characterization of unmodified poly (ethylene imines) (PEI)s in comparison with different oligosaccharide<br />(OS)-PEI-modified dendritic polymers (OM-PEI) using polyelectrolyte titration. It was found that the charge density (CD) as well as the<br />isoelectric points (IEP) was strongly influenced by the details of modification such as the type of oligosaccharide (Lactose or Maltose),<br />its structure and size (Maltose, Maltotriose or Maltoheptaose) and the PEI-OS ratio. Whereas the charge of unmodified PEI is cationic up<br />to pH of about 10, that means IEP of about 10, the IEP decreases with the influence of substituents. Further it is shown that the higher the<br />degree of chemically coupled OS units on the PEI surface, the lower is the charge density. For OM-PEIs the endpoint of titration<br />depended on the speed of titration which is consistent with a relatively slow rate of forming poly-ion complexes between modified PEIs<br />and titrants. For a good reproducibility the titration velocity should be not too high. Therefore a manual titration regime should be<br />preferred instead of an automatic “standard” titration regime with high titration velocity.
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Publisher
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Biointerface Research in Applied Chemistry
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Wikidata
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Citation
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Biointerface Research in Applied Chemistry 7 (2017) 1931-1938
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DOI
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http://biointerfaceresearch.com/?download=1908
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Tags
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poly(ethylene imine) characterization polyelectrolyte titration charge density
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