Random-packed structures of circular filamentous as a model of polymer rings

NICOLÁS A GARCÍA; LEOPOLDO R. GOMEZ; BARRAT, JEAN-LOUIS; THORSTEN POESCHEL

Grenoble

Workshop; Simulations of Small Angle Scatering; 2019

Institut Laue Langevin

Unraveling the packing structure of dense assemblies of semiflexible rings is not only fundamental for the dynamical description of polymers rings but also key tounderstanding biopackaging, such as observed in circular DNA inside viruses or genome folding. In this work, we use X-ray tomography to study disordered packings ofrubber bands in cylindrical containers. Using advanced computational tools we detect and study the rings configurations in the packings, characterizing the system atgeometrical and topological level. The degree of entanglement in the structures is quantified through minimal surfaces and generalized Voronoi tessellations, allowing theidentification of band's threadings and neighbors. We found that packings of short bands conform a liquid-like disordered structure, with short-range orientational order anda minor influence of the container. On the contrary, for longer rings, confinement forces the band?s folding and the rings interpenetrate and entangle. Most of the systemsare found to display a threading network which percolates the system. Interestingly, for long bands whose diameter doubles the diameter of the container, we found that allbands interpenetrate each other, in a complex fully-entangled structure.