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Main Title: Effect of ionic strength on rheological behavior of polymer-like cetyltrimethylammonium tosylate micellar solutions
Author(s): Macías, E. R.
Bautista, F.
Pérez-López, J. H.
Schulz, P. C.
Gradzielski, Michael
Manero, O.
Puig, J. E.
Escalante, J. I.
Type: Article
Language Code: en
Abstract: The influence of ionic strength on the rheological properties of polymer-like aqueous micellar solutions of cetyltrimethylammonium tosylate (CTAT) containing different salts (KCl, KBr, (COONa)2, K2SO4 or K3PO4) is investigated. The rheological behavior of the solutions is analyzed above the concentration where a micellar entanglement network is formed, varying surfactant and salt concentration, salt counterion valency and temperature. A master curve of the linear viscoelastic properties is obtained by multiple superposition of time, temperature, salt type, and surfactant and salt concentration. Application of the existent kinetic theory provides information suggesting that the micellar solutions are in the fast breaking regime (i.e., the relaxation is kinetically controlled) regardless of salt type and concentration. Moreover, these solutions exhibit shear-banding flow with a reduced stress plateau (σ/G0, being σ and G0 the shear stress and the plateau modulus, respectively) that increases with salt content and counterion valency. The zero-shear viscosity (η0) and the main relaxation time (τC) diminish with increasing salt content according to a step-like function, in which the number of steps increases with the salt counterion valence. In contrast, G0 only increases slightly with increasing salt content for the five salts employed. These results are discussed in terms of ionic strength and screening of the electrostatic-interactions caused by the addition of salt. In addition, it was found that the influence of anions on the viscoelastic properties of the polymer-like micelles follows the Hofmeister series commonly encountered in macromolecular and biological systems. This finding opens a challenge for scientists in the experimental and theoretical fields.
Issue Date: 2011
Date Available: 30-Jun-2016
DDC Class: 530 Physik
Journal Title: Soft matter
Publisher: Royal Society of Chemistry
Publisher Place: Cambridge
Volume: 7
Issue: 5
Publisher DOI: 10.1039/c0sm00739k
Page Start: 2094
Page End: 2102
EISSN: 1744-6848
ISSN: 1744-683X
Notes: Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.
Appears in Collections:Inst. Chemie » Publications

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