Abstract
Structural and rheological properties of viscoelastic fluids - transient networks filled with silica nanoparticles - have been studied. Three different viscoelastic matrices have been prepared: two connected and filled microemulsion networks with different droplet sizes (30 and 100 Å) and an aqueous telechelic tribloc copolymer gel. The two characterisation techniques, rheology and small angles neutron scattering allow us to link the rheological properties to the structure of this filled matrix. The rheological reinforcement factor of the gel is greater than the theorical predictions by Smallwood and Einstein, which apply to elastomers and dilute colloidal solutions. The structure measured by small angles neutron scattering proves that silica nanoparticles are well dispersed in the viscoelastic medium. A surfactant layer appears to be absorbed on the hydrophilic surface in the microemulsion case. This phenomenon leads to an increase of the number of active links per unit volume upon addition of silica nanoparticles. Macroscopically, this increase allows us to understand the shift of the percolation thresholds.