Formation of polyelectrolyte complexes with diethylaminoethyl dextran: Charge ratio and molar mass effect

•Anionic and cationic polyelectrolyte based on polysaccharide complexes are studied.•Zeta potential and ITC measurements show an atypical complexe stoichiometry (0.6).•Deviation from the 1:1 ratio is due to inaccessibility of some cationic charges.•PECs aggregates are evidenced by AsF4/MALS/DRI anal...

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Veröffentlicht in:Carbohydrate polymers 2014-11, Vol.113, p.217-224
Hauptverfasser: Le Cerf, Didier, Pepin, Anne Sophie, Niang, Pape Momar, Cristea, Mariana, Karakasyan-Dia, Carole, Picton, Luc
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Sprache:eng
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Zusammenfassung:•Anionic and cationic polyelectrolyte based on polysaccharide complexes are studied.•Zeta potential and ITC measurements show an atypical complexe stoichiometry (0.6).•Deviation from the 1:1 ratio is due to inaccessibility of some cationic charges.•PECs aggregates are evidenced by AsF4/MALS/DRI analysis. The formation of polyelectrolyte complexes (PECs) between carboxymethyl pullulan and DEAE Dextran, was investigated, in dilute solution, with emphasis on the effect of charge density (molar ratio or pH) and molar masses. Electrophoretic mobility measurements have evidenced that insoluble PECs (neutral electrophoretic mobility) occurs for charge ratio between 0.6 (excess of polycation) and 1 (stoichiometry usual value) according to the pH. This atypical result is explained by the inaccessibility of some permanent cationic charge when screened by pH dependant cationic ones (due to the Hoffman alkylation). Isothermal titration calorimetry (ITC) indicates an endothermic formation of PEC with a binding constant around 105Lmol−1. Finally asymmetrical flow field flow fractionation coupled on line with static multi angle light scattering (AF4/MALS) evidences soluble PECs with very large average molar masses and size around 100nm, in agreement with scrambled eggs multi-association between various polyelectrolyte chains.
ISSN:0144-8617
1879-1344
DOI:10.1016/j.carbpol.2014.07.015