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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.
Abstract:
The Rouse model is the foundational basis of much of modern polymer physics. The period alternative, the Kirkwood-Riseman model, is rarely mentioned in modern monographs. The models are qualitatively different. The models do not agree as to how many internal modes a polymer molecule has. In the Kirkwood-Riseman model, polymers in a shear field perform whole-body rotation; in the Rouse model, polymers respond to shear with an affine deformation. We use Brownian dynamics to show that the Kirkwood-Riseman model for chain motion is qualitatively correct. Contrary to the Rouse model, in shear flow, polymer coils rotate. Rouse modes are cross-correlated. The amplitudes and relaxation rates of Rouse modes depend on the shear rate. Several alternatives to Rouse modes as collective coordinates are discussed.
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