Rheological behavior of surfactant-based precursors of silica mesoporous materials

The linear and non-linear viscoelastic behaviors of polymer-like micellar solutions of cetyltrimethylammonium tosilate (CTAT) with added NaOH and tetraethyl orthosilicate (TEOS) to produce precursors of mesoporous materials are studied. The effect of TEOS/CTAT (T/C) ratio at fixed CTAT concentration...

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Bibliographic Details
Published in:Journal of colloid and interface science 2008-04, Vol.320 (1), p.290-297
Main Authors: Mendoza, L.D., Rabelero, M., Escalante, J.I., Macías, E.R., González-Álvarez, A., Bautista, F., Soltero, J.F.A., Puig, J.E.
Format: Article
Language:English
Subjects:
Chemistry
Colloidal additives
Colloidal state and disperse state
Exact sciences and technology
General and physical chemistry
Inter-macromolecular interactions
Micelles. Thin films
Polymer-like micelles
Porous materials
Surface physical chemistry
Viscoelastic behavior
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Summary:The linear and non-linear viscoelastic behaviors of polymer-like micellar solutions of cetyltrimethylammonium tosilate (CTAT) with added NaOH and tetraethyl orthosilicate (TEOS) to produce precursors of mesoporous materials are studied. The effect of TEOS/CTAT (T/C) ratio at fixed CTAT concentration, CTAT concentration at fixed T/C and aging time are reported. The systems show increasingly larger deviations from near-Maxwell behavior upon increasing T/C ratio, CTAT concentration and aging. Moreover, in steady and unsteady shear-flow, shear banding develops between two critical shear rates, which tend to fade as the T/C ratio and aging increase. The Granek–Cates model is employed to analyze linear viscoelastic behavior. The Bautista–Manero–Puig (BMP) model is used here to reproduce the steady and transient nonlinear rheology of these systems. We explain these results in terms of the changes in inter-macromolecular interactions that arise out of the presence of colloidal additives in the viscoelastic gel. The ordered mesoporous materials were identified by X-ray diffractometry (XRD) and high-resolution transmission electron microscopy. Micellar solutions to produce precursors of mesoporous materials are studied as function of TEOS/CTAT ratio, [CTAT] and aging time. Increasing the study parameters result into fading out of shear banding flow.
ISSN:0021-9797
1095-7103
DOI:10.1016/j.jcis.2007.12.024