Impact of Ni(OH)2 Platelike Particles on Lamellar Surfactant Mesophases and the Orientation of Their Mixtures under Elongational Flow

Abstract

This article describes the behavior under elongational flow of mixtures of lamellar fragments and platelike colloidal particles. Mixtures of a dialkyl chain cationic surfactant, DHTAC (15 wt %), and the nonionic surfactant Brij 97 (0.5 wt %) form dispersions of lamellar phase fragments, and these were studied in the presence of smaller platelike colloidal particles of Ni(OH)(2) stabilized with sodium polyacrylate. Small-angle neutron scattering was used to follow the changes in the lamellar phase fragments in the mixture under elongational flow. The addition of a small fraction of the Ni(OH)(2) dispersion resulted in significantly increased viscosity and reduced the structure and size of the lamellar fragments, and this effect was further enhanced because of the flow induced alignment. The behavior of the mixture under elongational flow is described, and the induced orientation is discussed in terms of order parameters at the different positions using spatially resolved small-angle scattering. The effect of flow rate on the orientational alignment in the mixture is also described.