Speaker
Description
Polymers present a wide variety of topologies: they can be cyclized, tied into knots, and can form entangled melts. Investigating such structures in the frame of biological systems, we incur into another layer of complexity, as polymers can display activity in the form of directed motion. Studying the interplay of activity and topology in polymers can bring a better understanding of biological system as well as help conceptualize tunable materials. We employ coarse-grained molecular dynamics simulations to study how complex topologies affect systems of tangentially active polymers, focusing on the rheological properties of highly entangled melts and the collapse behavior of knotted rings. We observe that the viscoelastic response of active melts depends marginally on their topology, contrary to passive melts, as energy intake becomes the main driver of the dynamics. Moreover, we find that the melt's rheology can be directly tuned with activity. The opposite behavior is observed in knots, where the role of topology is enhanced by activity: in fact, the collapse transition of active loops depends both on their knot complexity and family, although family has no role in determining the physical properties of passive polymer knots. This study shows that activity and topology heavily affect each other, and that both can be used to tune the properties of complex materials.