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Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
Stochastic entangled chain dynamics of dense polymer solutions
Demosthenes Kivotides1, S Louise Wilkin, Theo G Theofanous
1Department of Chemical Engineering, University of California, Santa Barbara, California 93117, USA. demos@engineering.ucsb.edu
The Journal of Chemical Physics
|October 19, 2010
Summary
We developed a new model for dense polymer solutions that accurately predicts chain behavior and relaxation times. This model captures entanglement effects, aligning well with experimental data and existing theories.
Area of Science:
- Polymer Physics
- Soft Matter Physics
Background:
- Dense polymer solutions exhibit complex dynamics influenced by chain entanglements and excluded volume effects.
- Existing models often require adjustable parameters or fail to capture all relevant physical phenomena.
Purpose of the Study:
- To develop a parameter-free model for entangled polymer solutions.
- To elucidate the role of entanglements in polymer dynamics and equilibrium properties.
- To provide a theoretical framework consistent with experimental observations.
Main Methods:
- Coarse-grained polymer dynamics incorporating hydrodynamic interactions.
- Forced Stokes equation for solvent dynamics.
- Pincus regime for chain elasticity and intermolecular potentials for excluded volume effects.
- Explicit geometric tracking of chain entanglements.
Main Results:
- The model predicts a novel slow relaxation mode due to entanglements, with excellent agreement to experimental timescales.
- Equilibrium chain size predictions also show strong agreement with experimental data.
- The number of entanglements (Π) scales with polymer volume fraction (φ) consistent with tube theory.
- Predicted chain size diminishes with concentration, supporting Flory's excluded volume screening hypothesis.
Conclusions:
- The proposed model successfully captures the dynamics and equilibrium properties of entangled polymer solutions without adjustable parameters.
- Entanglements are crucial for understanding the slow relaxation dynamics in these systems.
- The model validates key aspects of polymer solution theory, including excluded volume effects and scaling laws.
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