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Effects of Tethered Polymers on Dynamics of Nanoparticles in Unentangled Polymer Melts.

Publication ,  Journal Article
Ge, T; Rubinstein, M; Grest, GS
Published in: Macromolecules
August 2020

Polymer-tethered nanoparticles (NPs) are commonly added to a polymer matrix to improve material properties. Critical to the fabrication and processing of such composites is the mobility of the tethered NPs. Here we study the motion of tethered-NPs in unentangled polymer melts using molecular dynamics simulations, which offer a precise control of the grafted chain length Ng and the number z of grafted chains per particle. As Ng increases, there is a crossover from particle-dominated to tethered-chain-dominated terminal diffusion of NPs with the same z. The mean squared displacement of loosely tethered NPs in the case of tethered-chain dominated terminal diffusion exhibits two sub-diffusive regimes at intermediate time scales for small z. The first one at shorter time scales arises from the dynamical coupling of the particle and matrix chains, while the one at longer time scales is due to the participation of the particle in the dynamics of the tethered chains. The friction of loosely grafted chains in unentangled melts scales linearly with the total number of monomers in the chains, as the frictions of individual monomers are additive in the absence of hydrodynamic coupling. As more chains are grafted to a particle, hydrodynamic interactions between grafted chains emerge. As a result, there is a non-draining layer of hydrodynamically coupled chain segments surrounding the bare particle. Outside the non-draining layer is a free-draining layer of grafted chain segments with no hydrodynamic coupling. The boundary of the two layers is the stick surface where the shear stress due to the relative melt flow is balanced by the friction between grafted and melt chains in the interpenetration layer. The stick surface is located further away from the bare surface of the particle with higher grafting density.

Duke Scholars

Published In

Macromolecules

DOI

EISSN

1520-5835

ISSN

0024-9297

Publication Date

August 2020

Volume

53

Issue

16

Start / End Page

6898 / 6906

Related Subject Headings

  • Polymers
  • 40 Engineering
  • 34 Chemical sciences
  • 09 Engineering
  • 03 Chemical Sciences
 

Citation

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Ge, T., Rubinstein, M., & Grest, G. S. (2020). Effects of Tethered Polymers on Dynamics of Nanoparticles in Unentangled Polymer Melts. Macromolecules, 53(16), 6898–6906. https://doi.org/10.1021/acs.macromol.9b01921
Ge, Ting, Michael Rubinstein, and Gary S. Grest. “Effects of Tethered Polymers on Dynamics of Nanoparticles in Unentangled Polymer Melts.Macromolecules 53, no. 16 (August 2020): 6898–6906. https://doi.org/10.1021/acs.macromol.9b01921.
Ge T, Rubinstein M, Grest GS. Effects of Tethered Polymers on Dynamics of Nanoparticles in Unentangled Polymer Melts. Macromolecules. 2020 Aug;53(16):6898–906.
Ge, Ting, et al. “Effects of Tethered Polymers on Dynamics of Nanoparticles in Unentangled Polymer Melts.Macromolecules, vol. 53, no. 16, Aug. 2020, pp. 6898–906. Epmc, doi:10.1021/acs.macromol.9b01921.
Ge T, Rubinstein M, Grest GS. Effects of Tethered Polymers on Dynamics of Nanoparticles in Unentangled Polymer Melts. Macromolecules. 2020 Aug;53(16):6898–6906.
Journal cover image

Published In

Macromolecules

DOI

EISSN

1520-5835

ISSN

0024-9297

Publication Date

August 2020

Volume

53

Issue

16

Start / End Page

6898 / 6906

Related Subject Headings

  • Polymers
  • 40 Engineering
  • 34 Chemical sciences
  • 09 Engineering
  • 03 Chemical Sciences