TiO2 nanoparticle dispersions studied by sedimentation analysis: Hansen Parameters vs. DLVO interpretations - poster
Lucie Delforce¹, Evamaria Hofmann², Véronique Nardello-Rataj¹, Jean-Marie Aubry¹
1 Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 – UCCS – Unité de Catalyse et Chimie du Solide, Lille, France
2 Univ. Regensburg, Department of Physical Chemistry, 93051 Regensburg, Germany
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Titanium dioxide nanoparticles (TiO_² NPs) are among the most widely used NPs due to their interesting optical and catalytic properties. Most applications require their dispersion in fluid or solid matrixes. It is of first importance that NPs be and remain homogenously dispersed in the matrix to achieve optimal properties and stability. Hansen Dispersibility Parameters (HDP)¹ have been shown to be an effective approach for rationalizing and predicting the stability of various types of NP dispersions including TiO₂^1,2. However, it is not excluded that interparticle electrostatic interactions, not considered in Hansen’s approach, also play a significant role, especially for organic solvents having a notable dielectric constant^3–5. In this work, we discuss the respective contributions of DLVO and non-DLVO interactions in the stability of TiO₂ P25 nanoparticles dispersions, with a special emphasis on the relevance of the HDP concept to rationalize non-DLVO interactions in organic solvents.

For that purpose, zeta potential measurements in aqueous media and in 20 organic solvents are carried out to identify dispersions for which the stability can be explained by the DLVO theory from those for which the stability results from more specific NP-solvent interaction. These latter solvents are used to build the Hansen Dispersibility Sphere of TiO₂ P25 with a Turbiscan as stability analyser. This light scattering method provides detailed information regarding the destabilization mechanisms of dispersions i.e. agglomeration and flocculation of NPs, which reflect the balance between interparticle attraction and electrostatic repulsion^6–8.

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