Topology-Controlled Microphase Separation and Interconversion of Twist and Writhe Domains in Supercoiled Annealed Polyelectrolytes

In closed circular ribbonlike polymers such as deoxyribonucleic acid, twist and writhe are known to be largely determined by the polymer's bending and torsional rigidities, and they must sum to a topological constant. Using molecular simulations and an analytically solvable Landau theory, we study the interplay between ribbon topology and chemically annealed charges in a model polyelectrolyte. We show that the repulsions between like-charged acidic sites trigger phase separation and coexistence of supercoiling domains, in turn unveiling a complex phase diagram and providing a route to control the properties of deoxyribonucleic acid-based materials.