Tunable viscosity modification with diluted particles: When particles decrease the viscosity of complex fluids

While spherical particles are the most studied viscosity modifiers, they are well known only to increase viscosities, in particular at low concentrations. Extended studies and theories on non-spherical particles find a more complicated behavior, but still a steady increase. Involving platelets in combination with complex fluids displays an even more complex scenario that we analyze experimentally and theoretically as a function of platelet diameter, to find the underlying concepts. Using a broad toolbox of different techniques we were able to decrease the viscosity of crude oils although solid particles were added. This apparent contradiction could lead to a wider range of applications.