Rheological properties of TiO2 suspensions varied by shifting the electrostatic inter-particle interactions with an organic co-solvent

- The rheology of TiO2 suspensions is investigated for different compositions.
- A sufficient content of particles is needed to create a percolating network.
- The surface charge of TiO2 particles is affected by the presence of ethanol.
- Shear-thickening events can be moderated by the addition of ethanol.
- Adding ethanol annihilates the influence of the pH on the rheological properties.

The rheology of mineral suspensions is a key factor in many application fields. In particular, adjusting either the solid amount or the solvent composition appears as a possibility to control the rheological properties. These modifications should lead to variations of the electrostatic inter-particle interactions influencing thus the suspensions viscoelastic behavior. TiO2 suspensions were firstly formulated in water by adjusting the pH close to the isoelectric point of the TiO2 nanoparticles. The influence of the solid amount as well as the pH was study and coupled to the rheological properties of aqueous suspensions. In a second time, a part of water was substituted by an organic solvent (i.e. ethanol). Rheological measurements were performed and coupled to the zeta potentials of the TiO2 into different solvents. The rheological properties of TiO2 suspensions were adjusted by varying the electrostatic inter-particle interactions. The pH has to be close enough to the TiO2 isoelectric point and the particle concentration high enough to create a percolating network. With adding ethanol, transient shear thickening is suppressed and, even far from the isoelectric point, the resulting flocculated suspensions show high yield stresses over a large pH range.

110