Breakdown of the Continuum Stokes−Einstein Relation for Nanoparticle Diffusion

Cadmium selenide nanoparticles are found to diffuse approximately 200 times faster in a polymeric liquid than predicted by the Stokes−Einstein relation. This remarkable behavior is hypothesized to be due to the nanoparticles being smaller than the entanglement mesh to create a frictional drag that does not follow continuum expectations, in line with a theoretical calculation presented before. This is one of the first demonstrations of X-ray photo correlation spectroscopy applied to polymeric liquids, which we use to explain the simultaneous 60% viscosity reduction of the mixture through a proposed constraint release mechanism.