Experimental measurement of coil-rod-coil block copolymer tracer diffusion through entangled coil homopolymers

Muzhou Wang, Ksenia Timachova, Bradley D. Olsen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The diffusion of coil-rod-coil triblock copolymers in entangled coil homopolymers is experimentally measured and demonstrated to be significantly slower than rod or coil homopolymers of the same molecular weight. A model coil-rod-coil triblock was prepared by expressing rodlike alanine-rich α-helical polypeptides in E. coli and conjugating coil-like poly(ethylene oxide) (PEO) to both ends to form coil-rod-coil triblock copolymers. Tracer diffusion through entangled PEO homopolymer solutions was measured using forced Rayleigh scattering at various rod lengths and coil molecular weights for the tracer, and various concentrations for the coil homopolymer solutions. For rod lengths, L, that are close to the entanglementh length, a, the ratio between the diffusivity of a triblock and the diffusivity of a coil homopolymer of the same molecular weight decreases monotonically and is only a function of L/a, in quantitative agreement with previous simulation results. For large rod lengths, diffusion follows an arm retraction scaling, which is also consistent with previous theoretical predictions. These experimental results support the key predictions of theory and simulation, suggesting that the mismatch in curvature between rod and coil entanglement tubes leads to the observed diffusional slowing.

Original languageEnglish (US)
Pages (from-to)1651-1658
Number of pages8
JournalMacromolecules
Volume46
Issue number4
DOIs
StatePublished - Feb 26 2013

ASJC Scopus subject areas

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

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