Effect of screening of intermicellar interactions on the linear and nonlinear rheology of a viscoelastic gel

Bandyopadhyay, Ranjini; Sood, A.K.

Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/4653

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DC Field	Value	Language
dc.contributor.author	Bandyopadhyay, Ranjini	-
dc.contributor.author	Sood, A.K.	-
dc.date.accessioned	2012-06-09T09:39:51Z	-
dc.date.available	2012-06-09T09:39:51Z	-
dc.date.issued	2003	-
dc.identifier.citation	Langmuir, 2003, Vol.19, p3121-3127	en
dc.identifier.issn	0743-7463	-
dc.identifier.issn	1520-5827 (Online)	-
dc.identifier.uri	http://hdl.handle.net/2289/4653	-
dc.description	Restricted Access.	en
dc.description.abstract	We report our studies of the linear and nonlinear rheology of aqueous solutions of the surfactant cetyl trimethylammonium tosylate (CTAT) with varying amounts of sodium chloride (NaCl). The CTAT concentration is fixed at 42mM and the salt concentration is varied between 0mM to 120mM. On increasing the salt (NaCl) concentration, we see three distinct regimes in the zero-shear viscosity and the high frequency plateau modulus data. In regime I, the zero-shear viscosity shows a weak increase with salt concentration due to enhanced micellar growth. The decrease in the zero-shear viscosities with salt concentration in regimes I I and III can be explained in terms of inter-micellar branching. The most intriguing feature of our data however, is the anomalous behavior of the high frequency plateau modulus in regime II (0.12 $\le \frac{[NaCl]}{[CTAT]} \le$ 1. 42). In this regime, the plateau modulus {\it increases} with an increase in NaCl concentration. This is highly counter-intuitive, since the correlation length of concentration fluctuations and hence the plateau modulus $G_{\circ}$ are not expected to change appreciably in the semi-dilute regime. We propose to explain the changes in regime II in terms of the unbinding of the organic counterions (tosylate) from the CTA$^{+}$ surfaces on the addition of NaCl. In the nonlinear flow curves of the samples with high salt content, significant deviations from the predictions of the Giesekus model for entangled micelles are observed.	en
dc.language.iso	en	en
dc.publisher	American Chemical Society	en
dc.relation.uri	http://arxiv.org/abs/cond-mat/0012473	en
dc.rights	2003 American Chemical Society	en
dc.title	Effect of screening of intermicellar interactions on the linear and nonlinear rheology of a viscoelastic gel	en
dc.type	Article	en
Appears in Collections:	Research Papers (SCM)

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