Collective Dynamics in Active Polar Polymer Assemblies

Abstract: Active polymers respond to spatial activity gradients by autonomously migrating, a behavior central to biological self-organization and the design of intelligent synthetic materials. Using Brownian dynamics simulations, we investigate how the structure and propulsion direction of tangentially driven active polymers (TDAPs) determine their collective response to activity gradients. We show that TDAP assemblies exhibit strikingly different behaviors based on their organization: inward-directed arms form compact bundles that accumulate in low-activity regions, whereas outward-directed arms assemble into asters that undergo directed motion toward high-activity regions. Remarkably, mixed structures, comprising both inward- and outward-directed arms, display enhanced accumulation in the high-activity regions due to cooperative effects. In addition, we show that two-arm polymers accumulate within a finite-width active slab embedded in a passive background, and as the slab narrows, the polymers reorient perpendicular to the slab boundaries to remain within the active regions. Our results establish a fundamental link between polymer geometry and emergent transport, providing key design principles for programmable active materials.