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Title: Diffusion of Sticky Nanoparticles in a Polymer Melt: Crossover from Suppressed to Enhanced Transport

The self-diffusion of a single large particle in a fluid is usually described by the classic Stokes–Einstein (SE) hydrodynamic relation. However, there are many fluids where the SE prediction for nanoparticles diffusion fails. These systems include diffusion of nanoparticles in porous media, in entangled and unentangled polymer melts and solutions, and protein diffusion in biological environments. A fundamental understanding of the microscopic parameters that govern nanoparticle diffusion is relevant to a wide range of applications. Here in this work, we present experimental measurements of the tracer diffusion coefficient of small and large nanoparticles that experience strong attractions with unentangled and entangled polymer melt matrices. For the small nanoparticle system, a crossover from suppressed to enhanced diffusion is observed with increasing polymer molecular weight. We interpret these observations based on our theoretical and simulation insights of the preceding article (paper 1) as a result of a crossover from an effective hydrodynamic core–shell to a nonhydrodynamic vehicle mechanism of transport, with the latter strongly dependent on polymer–nanoparticle desorption time. In conclusion, a general zeroth-order qualitative picture for small sticky nanoparticle diffusion in polymer melts is proposed.
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [3] ;  [2] ; ORCiD logo [4] ;  [5] ;  [6] ; ORCiD logo [3] ; ORCiD logo [7]
  1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS)
  4. Michigan State Univ., East Lansing, MI (United States). Dept. of Chemical Engineering and Materials Science
  5. California Inst. of Technology (CalTech), Pasadena, CA (United States). Division of Chemistry and Chemical Engineering
  6. Univ. of Illinois, Urbana, IL (United States). Dept. of Materials Science and Chemistry, Frederick Seitz Materials Research Lab.
  7. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy, and Dept. of Chemistry; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 51; Journal Issue: 6; Journal ID: ISSN 0024-9297
American Chemical Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
OSTI Identifier: