Entangled chain dynamics of polymer knots in extensional flow

Demosthenes Kivotides, S. Louise Wilkin, Theo G. Theofanous

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

We formulate a coarse-grained molecular-dynamics model of polymer chains in solution that includes hydrodynamic interactions, thermal fluctuations, nonlinear elasticity, and topology-preserving solvent mediated excluded volume interactions. The latter involve a combination of potential forces with explicit geometric detection and tracking of chain entanglements. By solving this model with numerical and computational methods, we study the physics of polymer knots in a strong extensional flow (Deborah number De=1.6). We show that knots slow down the stretching of individual polymers by obstructing via entanglements the "natural," unraveling, and flow-induced chain motions. Moreover, the steady-state polymer length and polymer-induced stress values are smaller in knotted chains than in topologically trivial chains. We indicate the molecular processes via which the rate of knot tightening affects the rheology of the solution.
Original languageEnglish
Article number041808
Number of pages16
JournalPhysical Review E
Volume80
Issue number4
DOIs
Publication statusPublished - 29 Oct 2009

Keywords

  • polymers
  • degrees of freedom (mechanics)
  • elasticity
  • fluid dynamics
  • natural polymers
  • numerical methods
  • chain dynamics
  • chain entanglements
  • chain motions
  • coarse-grained
  • Deborah numbers
  • detection and tracking
  • excluded-volume interactions
  • extensional flows
  • hydrodynamic interaction
  • induced stress
  • molecular process
  • molecular-dynamics model
  • nonlinear elasticity
  • polymer chains
  • polymer length
  • potential forces
  • thermal fluctuations

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