Breakdown of the continuum stokes-einstein relation for nanoparticle diffusion.

Tuteja, Anish; Mackay, Michael E; Narayanan, Suresh; Asokan, Subashini; Wong, Michael S · Nano Lett · 2007

basic_science · Level V

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Abstract

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.