Diffusion mechanisms of entangled rod-coil diblock copolymers

Muzhou Wang, Ksenia Timachova, Bradley D. Olsen*

*Corresponding author for this work

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Mechanisms of entangled rod-coil diblock copolymer diffusion are investigated using tracer diffusion simulations and experiments in a matrix of entangled coil homopolymers, demonstrating that the diffusion mechanisms first identified in coil-rod-coil triblocks are universal for various molecular architectures. Diffusion measurements were performed using both Kremer-Grest molecular dynamics simulations and forced Rayleigh scattering experiments. In the large rod regime, diffusivity decreases exponentially with increasing coil size as predicted by an arm retraction mechanism. The ratio of diblock to rod homopolymer diffusivity was approximately equal to the ratio for triblocks squared, suggesting that the two coil blocks of the coil-rod-coil triblock relax independently. In the small rod regime, both experiments and simulation show that the slowing of diffusion with increasing rod length is the same for rod-coil diblock and coil-rod-coil triblock copolymers. This behavior occurs because both types of molecules reptate through tubes with Gaussian statistics, so diffusional slowing results from entropic barriers to rod reptation through curved sections of the entanglement tube.

Original languageEnglish (US)
Pages (from-to)5694-5701
Number of pages8
JournalMacromolecules
Volume46
Issue number14
DOIs
StatePublished - Jul 23 2013

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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