Comparing the structure and dynamics of single and catenated partially active ring polymers.

Area of Science:

• Polymer Physics
• Soft Matter Physics
• Computational Biophysics

Background:

• Active polymers exhibit complex dynamics driven by internal forces and topology.
• Understanding the interplay between activity, topology, and polymer conformation is crucial for designing active materials.

Purpose of the Study:

• Investigate the conformational changes and dynamics of semiflexible active ring polymers.
• Explore the effects of monomer activity distribution (block vs. random) and ring size on polymer behavior.
• Analyze the influence of catenation on active ring polymer systems.

Main Methods:

• Langevin dynamics simulations using the Kremer-Grest model.
• Systematic variation of ring size (N ≤ 200) and activity strength (Peclet number, Pe).
• Analysis of active monomer distribution and catenation scenarios (symmetric and asymmetric).

Main Results:

• Non-monotonic radius of gyration (Rg) observed: initial shrinkage followed by swelling with increasing activity.
• Maximal shrinkage scales with chain length for block copolymers, but is length-independent for random copolymers.
• Active rings show altered asphericity depending on size; catenation constrains swelling and influences passive ring shape.

Conclusions:

• The spatial distribution and number of active monomers significantly impact ring polymer conformation.
• Catenation acts as a mechanical constraint, modifying the behavior of active and passive rings.
• Active ring polymers offer tunable properties, with potential applications in active materials and soft robotics.