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Li L, Harnau L, Rosenfeldt S, Ballauff M. Effective interaction of charged platelets in aqueous solution: investigations of colloid laponite suspensions by static light scattering and small-angle x-ray scattering. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 72:051504. [PMID: 16383608 DOI: 10.1103/physreve.72.051504] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Indexed: 05/05/2023]
Abstract
We study dilute aqueous solutions of charged disklike mineral particles (laponite) by a combination of static light scattering (SLS) and small-angle x-ray scattering (SAXS). Laponite solutions are known to form gels above a certain critical concentration that must be described as nonequilibrium states. Here we focus on the investigation by SLS and SAXS at concentrations below gelation (c<0.016 g/L) and at low concentrations of added salt (0.001M and 0.005M). Thus, we have obtained the scattering function of single Laponite platelets as well as the structure factor describing their interaction at finite concentration. A detailed analysis of the combined sets of data proves that the solutions are in a well-defined equilibrium state. Moreover, this analysis demonstrates the internal consistency and accuracy of the scattering functions obtained at finite concentrations. We find that laponite particles interact through an effective pair potential that is attractive on short range but repulsive on longer range. This finding demonstrates that Laponite solutions exhibit only a limited stability at the concentration of added salt used herein. Raising the ionic strength to 0.005M already leads to slow flocculation as is evidenced from the enhanced scattering intensity at smallest scattering angles. All data strongly suggest that the gelation occurring at higher concentration is related to aggregation.
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Affiliation(s)
- Li Li
- Physikalische Chemie I, University of Bayreuth, 95440 Bayreuth, Germany
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Prabhu VM, Amis EJ, Bossev DP, Rosov N. Counterion associative behavior with flexible polyelectrolytes. J Chem Phys 2004; 121:4424-9. [PMID: 15332993 DOI: 10.1063/1.1776556] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
At low ionic strength, organic counterions dress a flexible charged polymer as measured directly by small-angle neutron scattering and neutron spin-echo spectroscopy. This dressed state, quantified by the concentration dependence of the static correlation length, illustrates the polymer-counterion coupled nature on the nanometer length scale. The counterions, made visible by selective hydrogen and deuterium labeling, undress from the polymeric template by addition of sodium chloride. The addition of this electrolyte leads to two effects: increased Debye electrostatic screening and decoupled organic counterion-polymer correlations. Neutron spin-echo spectroscopy measures a slowing down of the effective diffusion coefficient of the labeled counterions at the length scale of 8 nm, the static correlation length, indicating the nanosecond counterion dynamics mimics the polymer. These experiments, performed with semidilute solutions of tetramethylammonium poly(styrene sulfonate) [(h-TMA(+)) d-PSS], apply to relevant biopolymers including single and double stranded DNA and unfolded proteins, which undergo orchestrated dynamics of counterions and chain segments to fold, unfold, and assemble.
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Affiliation(s)
- Vivek M Prabhu
- Polymers Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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Tiihonen J, Markkanen I, Kärki A, Äänismaa P, Laatikainen M, Paatero E. Modelling the sorption of water–ethanol mixtures in cross-linked ionic and neutral polymers. Chem Eng Sci 2002. [DOI: 10.1016/s0009-2509(02)00097-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Kassapidou K, Jesse W, Kuil ME, Lapp A, Egelhaaf S, van der Maarel JRC. Structure and Charge Distribution in DNA and Poly(styrenesulfonate) Aqueous Solutions. Macromolecules 1997. [DOI: 10.1021/ma9617126] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- K. Kassapidou
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands, Laboratoire Léon Brillouin, CENSaclay, 91191 Gif sur Yvette Cedex, France, and Institute Max von Laue−Paul Langevin, 156 X, 38042 Grenoble Cedex, France
| | - W. Jesse
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands, Laboratoire Léon Brillouin, CENSaclay, 91191 Gif sur Yvette Cedex, France, and Institute Max von Laue−Paul Langevin, 156 X, 38042 Grenoble Cedex, France
| | - M. E. Kuil
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands, Laboratoire Léon Brillouin, CENSaclay, 91191 Gif sur Yvette Cedex, France, and Institute Max von Laue−Paul Langevin, 156 X, 38042 Grenoble Cedex, France
| | - A. Lapp
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands, Laboratoire Léon Brillouin, CENSaclay, 91191 Gif sur Yvette Cedex, France, and Institute Max von Laue−Paul Langevin, 156 X, 38042 Grenoble Cedex, France
| | - S. Egelhaaf
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands, Laboratoire Léon Brillouin, CENSaclay, 91191 Gif sur Yvette Cedex, France, and Institute Max von Laue−Paul Langevin, 156 X, 38042 Grenoble Cedex, France
| | - J. R. C. van der Maarel
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands, Laboratoire Léon Brillouin, CENSaclay, 91191 Gif sur Yvette Cedex, France, and Institute Max von Laue−Paul Langevin, 156 X, 38042 Grenoble Cedex, France
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