Nonequilibrium relaxation of soft responsive colloids

Area of Science:

• Soft Matter Physics
• Colloidal Science
• Statistical Mechanics

Background:

• Stimuli-responsive macromolecules exhibit conformational changes and multi-stability, crucial for developing advanced soft functional materials.
• Understanding the nonequilibrium dynamics of such systems under external fields is essential for material design.

Purpose of the Study:

• To introduce a mean-field dynamical density functional theory for responsive colloids.
• To investigate the coupling between translational and conformational dynamics during relaxation in time-dependent external fields.

Main Methods:

• Developed a mean-field dynamical density functional theory for soft Gaussian particles.
• Simulated colloidal dispersions between confining walls under time-dependent gravitational and osmotic fields.
• Validated theoretical findings against particle-based Brownian dynamics simulations.

Main Results:

• Observed rich relaxation behaviors in colloidal dispersions, showing excellent agreement with simulations.
• Identified time-asymmetric relaxations for the activation and deactivation of external potentials.
• Demonstrated that relaxation asymmetry is tunable via the ratio of translational and conformational diffusion time scales.

Conclusions:

• The developed theory accurately captures the nonequilibrium relaxation dynamics of complex soft matter.
• The findings provide insights into hierarchical relaxations in systems with multiple degrees of freedom.
• This work offers a framework for designing and controlling soft functional materials with responsive properties.