The dynamic steady-states of polar self-propelled filaments confined in 2D flexible vesicles*

Active materials exhibit spectacular spatiotemporal dynamics not possible in equilibrium systems. While it is well-known that these behaviors can be dramatically altered by boundaries, most such studies have focused on rigid boundaries or active agents that lack internal degrees of freedom. In this work we investigate the relationship between boundary and agent degrees of freedom, by simulating self-propelled semiflexible filaments confined within flexible vesicles in two dimensions. We observe a diverse array of emergent behaviors depending on filament properties (density, length, flexibility, and activity) as well as container size and flexibility. While some of these behaviors can be understood based on the intrinsic time and length scales associated with individual filaments or the boundary, others arise through a complex interplay between activity and deformations of the boundary or filamments, leading to new classes of dynamical self-organized states.