Effect of adjuvants on the contact properties of colloidal particles
Colloidal suspensions are ubiquitous in our environment (cosmetics, foods, fresh building materials, environmental fluids, …). When the solid volume concentration is high enough (30% or more) the rheology of these materials is controlled by the interactions between particles, whether they are contact or short range. In many practical applications, polymers are added (adjuvantation) to the suspension to adapt its rheology to its implementation or use.
Our understanding of the physics of these adjuvanted suspensions remains limited because of the experimental difficulties to overcome to characterize the interactions between particles: these suspensions are dense and opaque and the forces between particles can be of the order of a few piconewtons for separations of a few angstroms. The rheology of colloidal suspensions is thus a very active multidisciplinary research field.
By combining optical tweezers measurements, rheometry tests and confocal microscopy observations, our team has recently shown that the particular rheology of silica particle suspensions in a saline solution is due to the existence of aging adhesive contacts between the particles [1, 2].
The objective of this experimental thesis is to build on these results to study the effect of the addition of a polymeric additive on the properties of a suspension of silica particles.