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 language | English |
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Article number | 041808 |
Number of pages | 16 |
Journal | Physical Review E |
Volume | 80 |
Issue number | 4 |
DOIs | |
Publication status | Published - 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