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Title: On the mesoscopic origins of high viscosities in some polyelectrolyte-surfactant mixtures

Abstract

Oppositely charged polyelectrolyte (PE) surfactant mixtures allow the control of rheological parameters of a solution even at fairly low concentrations. For example, addition of 0.3 wt. % of anionic surfactant to a 1 wt. % solution of the polycation JR 400 increases the viscosity by 4 orders of magnitude. Recently, we could show that this increase is related to the formation of mixed, rod-like PE/surfactant aggregates which interconnect several polyelectrolyte chains [Hoffmann et al., Europhys. Lett. 104, 28001 (2013)]. In this paper, we refine our structural model of the aggregates to obtain a more consistent picture of their internal structure for different anionic surfactants. Combining small angle neutron scattering (SANS) and neutron spin-echo (NSE) allows us to determine the size of the aggregates. By comparing different contrasts, the internal structure of the aggregates can be elucidated and it is seen that the PE in the aggregates retains a relatively high freedom of movement. We proceeded to investigate the influence of the surfactant concentration and the surfactant type on structure and dynamics of the mixed aggregates. It is seen that the structural parameters of the aggregates depend very little on the surfactant concentration and headgroup. However, it is crucial to incorporate a sufficientmore » amount of PE in the aggregates to increase the viscosity of the aggregates. By comparing viscous samples at 1 wt. % PE concentration with samples at a PE concentration of 0.3 wt. %, where no significant increase in viscosity is observed, we find that similar aggregates are formed already at this lower PE concentrations. However, the amount of PE incorporated in them is insufficient to interconnect several PE chains and therefore, they do not increase viscosity. So, our detailed investigation combining contrast variation SANS and NSE does not only allow to explain the viscosity behavior but also to deduced detailed information regarding the structures and the dynamics especially of the polyelectrolyte within the complexes.« less

Authors:
 [1]; ; ; ;  [2];  [1];  [3];  [1]
  1. Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin (Germany)
  2. Institut Max von Laue-Paul Langevin (ILL), F-38042 Grenoble Cedex 9 (France)
  3. Germany
Publication Date:
OSTI Identifier:
22493555
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 143; Journal Issue: 7; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; COMPARATIVE EVALUATIONS; CONCENTRATION RATIO; NEUTRON DIFFRACTION; NEUTRON SPECTROSCOPY; NEUTRONS; SMALL ANGLE SCATTERING; SOLUTIONS; SPIN ECHO; STRUCTURAL MODELS; SURFACTANTS; VARIATIONS; VISCOSITY

Citation Formats

Hoffmann, Ingo, Institut Max von Laue-Paul Langevin, Farago, Bela, Schweins, Ralf, Falus, Peter, Sharp, Melissa, Prévost, Sylvain, Helmholtz-Zentrum Berlin, D-14109 Berlin, and Gradzielski, Michael. On the mesoscopic origins of high viscosities in some polyelectrolyte-surfactant mixtures. United States: N. p., 2015. Web. doi:10.1063/1.4928583.
Hoffmann, Ingo, Institut Max von Laue-Paul Langevin, Farago, Bela, Schweins, Ralf, Falus, Peter, Sharp, Melissa, Prévost, Sylvain, Helmholtz-Zentrum Berlin, D-14109 Berlin, & Gradzielski, Michael. On the mesoscopic origins of high viscosities in some polyelectrolyte-surfactant mixtures. United States. doi:10.1063/1.4928583.
Hoffmann, Ingo, Institut Max von Laue-Paul Langevin, Farago, Bela, Schweins, Ralf, Falus, Peter, Sharp, Melissa, Prévost, Sylvain, Helmholtz-Zentrum Berlin, D-14109 Berlin, and Gradzielski, Michael. Fri . "On the mesoscopic origins of high viscosities in some polyelectrolyte-surfactant mixtures". United States. doi:10.1063/1.4928583.
@article{osti_22493555,
title = {On the mesoscopic origins of high viscosities in some polyelectrolyte-surfactant mixtures},
author = {Hoffmann, Ingo and Institut Max von Laue-Paul Langevin and Farago, Bela and Schweins, Ralf and Falus, Peter and Sharp, Melissa and Prévost, Sylvain and Helmholtz-Zentrum Berlin, D-14109 Berlin and Gradzielski, Michael},
abstractNote = {Oppositely charged polyelectrolyte (PE) surfactant mixtures allow the control of rheological parameters of a solution even at fairly low concentrations. For example, addition of 0.3 wt. % of anionic surfactant to a 1 wt. % solution of the polycation JR 400 increases the viscosity by 4 orders of magnitude. Recently, we could show that this increase is related to the formation of mixed, rod-like PE/surfactant aggregates which interconnect several polyelectrolyte chains [Hoffmann et al., Europhys. Lett. 104, 28001 (2013)]. In this paper, we refine our structural model of the aggregates to obtain a more consistent picture of their internal structure for different anionic surfactants. Combining small angle neutron scattering (SANS) and neutron spin-echo (NSE) allows us to determine the size of the aggregates. By comparing different contrasts, the internal structure of the aggregates can be elucidated and it is seen that the PE in the aggregates retains a relatively high freedom of movement. We proceeded to investigate the influence of the surfactant concentration and the surfactant type on structure and dynamics of the mixed aggregates. It is seen that the structural parameters of the aggregates depend very little on the surfactant concentration and headgroup. However, it is crucial to incorporate a sufficient amount of PE in the aggregates to increase the viscosity of the aggregates. By comparing viscous samples at 1 wt. % PE concentration with samples at a PE concentration of 0.3 wt. %, where no significant increase in viscosity is observed, we find that similar aggregates are formed already at this lower PE concentrations. However, the amount of PE incorporated in them is insufficient to interconnect several PE chains and therefore, they do not increase viscosity. So, our detailed investigation combining contrast variation SANS and NSE does not only allow to explain the viscosity behavior but also to deduced detailed information regarding the structures and the dynamics especially of the polyelectrolyte within the complexes.},
doi = {10.1063/1.4928583},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 7,
volume = 143,
place = {United States},
year = {2015},
month = {8}
}