Memory in the relaxation of a polymer density modulation

Area of Science:

• Polymer Physics
• Soft Matter Physics
• Computational Materials Science

Background:

• Dynamic self-consistent field theory (SCFT) often assumes density alone characterizes polymer configurations.
• Understanding polymer dynamics and relaxation processes is crucial for material properties.

Purpose of the Study:

• To investigate the relaxation of density modulations in polymer systems without nonbonded interactions.
• To determine if density alone is sufficient to describe polymer system configurations.
• To develop analytical models that accurately predict polymer dynamics.

Main Methods:

• Particle-based simulations of a coarse-grained polymer model.
• Analytical considerations using Linear-Response Theory (LRT) and the Rouse model.
• Development of a dynamic density-functional theory based on single-chain configurations.

Main Results:

• Identical shallow density modulations prepared differently exhibit nonexponential decay.
• Density alone is insufficient to characterize the polymer system's configuration.
• Analytical models (LRT, Rouse) quantitatively agree with simulation results.

Conclusions:

• Polymer system dynamics are dependent on preparation history, not just density.
• Linear-Response Theory provides a framework equivalent to generalized model-B dynamics.
• Dynamic density-functional theory using full configuration distributions offers a memory-free description accounting for preparation dependence.