title: Rheological behavior of surfactant-based precursors of silica mesoporous materials.
abstract: 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.
authors.affiliation: Departamento de Ingeniería Química, Universidad de Guadalajara, Boul. M. García-Barragán 1451, Guadalajara, Jal. 44430, México.
authors.forename: L D
authors.initials: LD
authors.lastname: Mendoza
authors.forename: M
authors.initials: M
authors.lastname: Rabelero
authors.forename: J I
authors.initials: JI
authors.lastname: Escalante
authors.forename: E R
authors.initials: ER
authors.lastname: Macías
authors.forename: A
authors.initials: A
authors.lastname: González-Alvarez
authors.forename: F
authors.initials: F
authors.lastname: Bautista
authors.forename: J F A
authors.initials: JF
authors.lastname: Soltero
authors.forename: J E
authors.initials: JE
authors.lastname: Puig