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The Kirkwood-Riseman Model of Polymer Solution Dynamics Is Qualitatively Correct.
1Department of Physics, Worcester Polytechnic Institute, Worcester, MA 01609-2280, USA.
Polymers
|May 13, 2023
Summary
The Kirkwood-Riseman model accurately describes polymer motion in shear flow, showing coils rotate, unlike the Rouse model. This study validates the Kirkwood-Riseman model using Brownian dynamics simulations.
Area of Science:
- Polymer Physics
- Soft Matter Physics
- Rheology
Background:
- The Rouse model is a cornerstone of modern polymer physics, describing polymer dynamics.
- The Kirkwood-Riseman model offers an alternative perspective on polymer dynamics but is less frequently discussed.
- Key differences exist between the models regarding internal modes and response to shear fields.
Purpose of the Study:
- To investigate the validity of the Kirkwood-Riseman model for polymer chain motion in shear flow.
- To compare the predictions of the Kirkwood-Riseman and Rouse models under shear conditions.
- To elucidate the behavior of polymer coils in shear fields.
Main Methods:
- Brownian dynamics simulations were employed to model polymer behavior.
- The study focused on analyzing polymer motion within a shear flow environment.
- Simulations were used to observe and quantify polymer coil rotation and deformation.
Main Results:
- Brownian dynamics simulations support the qualitative correctness of the Kirkwood-Riseman model.
- In shear flow, polymer coils exhibit whole-body rotation, consistent with the Kirkwood-Riseman model.
- The Rouse model's prediction of affine deformation is challenged; Rouse modes are found to be cross-correlated and shear-rate dependent.
Conclusions:
- The Kirkwood-Riseman model provides a more accurate description of polymer dynamics in shear flow than the Rouse model.
- Polymer coils rotate in shear flow, a phenomenon captured by the Kirkwood-Riseman model.
- The study suggests exploring alternatives to Rouse modes as collective coordinates for describing polymer dynamics.
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