In Situ Rheology of Complex Fluids Under High Pressure

Complex fluids are ubiquitous in our everyday life. In some biological and engineering processes, very thin fluid films are present and often they experience high pressure and shear. Such fluids include polymer or micellar solutions and mixtures of polymer/oligomers. Their rheology across different length scales, from the nanometre to the microscale, is difficult to resolve using conventional techniques when there are spatial heterogeneities. Fluorescence anisotropy and molecular probes of differing sizes provide the opportunity to study the local physics of such fluids, under high pressures and shear stresses. This work presents the local rheology of a complex fluid system under high shear stress, using fluorescence anisotropy measurements, at pressures up to 1 GPa. The effects of fluid composition and shear stress are investigated.