Shear-banding and superdiffusivity in entangled polymer solutions

Seunghwan Shin, Kevin D. Dorfman, Xiang Cheng

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Using high-resolution confocal rheometry, we study the shear profiles of well-entangled DNA solutions under large-amplitude oscillatory shear in a rectilinear planar shear cell. With increasing Weissenberg number (Wi), we observe successive transitions from normal Newtonian linear shear profiles to wall-slip dominant shear profiles and, finally, to shear-banding profiles at high Wi. To investigate the microscopic origin of the observed shear banding, we study the dynamics of micron-sized tracers embedded in DNA solutions. Surprisingly, tracer particles in the shear frame exhibit transient superdiffusivity and strong dynamic heterogeneity. The probability distribution functions of particle displacements follow a power-law scaling at large displacements, indicating a Lévy-walk-type motion, reminiscent of tracer dynamics in entangled wormlike micelle solutions and sheared colloidal glasses. We further characterize the length and time scales associated with the abnormal dynamics of tracer particles. We hypothesize that the unusual particle dynamics arise from localized shear-induced chain disentanglement.

Original languageEnglish (US)
Article number062503
JournalPhysical Review E
Volume96
Issue number6
DOIs
StatePublished - Dec 21 2017

Bibliographical note

Funding Information:
We thank F. Bates, C. Macosko, C. Schroeder, and L. Walker for fruitful discussions and P. Agrawal for preparing the etched silicon wafer. S.S. acknowledges financial support from the Kwanjeong Educational Foundation. The work was supported by NSF CBET-1700771. Portions of this work were performed in UMN Nanofabrication Center, which receives a partial support from NSF National Nanotechnology Infrastructure Network and the UMN College of Science and Engineering Polymer Characterization Facility, which receives capital equipment funding from the NSF through the UMN MRSEC program (Grant No. DMR-1420013).

Funding Information:
We thank F. Bates, C. Macosko, C. Schroeder, and L. Walker for fruitful discussions and P. Agrawal for preparing the etched silicon wafer. S.S. acknowledges financial support from the Kwanjeong Educational Foundation. The work was supported by NSF CBET-1700771. Portions of this work were performed in UMN Nanofabrication Center, which receives a partial support from NSF National Nanotechnology Infrastructure Network and the UMN College of Science and Engineering Polymer Characterization Facility, which receives capital equipment funding from the NSF through the UMN MRSEC program (Grant No. DMR-1420013).

Publisher Copyright:
© 2017 American Physical Society.

How much support was provided by MRSEC?

  • Shared

Reporting period for MRSEC

  • Period 4

PubMed: MeSH publication types

  • Journal Article

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