Mixing, segregation, and collapse transitions of interacting copolymer rings

TL;DR

This paper investigates the phase behavior of two interacting ring polymers, identifying three equilibrium phases with distinct spatial and topological properties through simulations and combinatorial analysis.

Contribution

It introduces a lattice model and simulation approach to classify phases and analyze topological features of interacting ring polymers.

Findings

Identified three equilibrium phases: segregated-expanded, segregated-collapsed, and mixed.

Located phase boundaries and discussed their critical nature.

Showed topological differences, with linking in the mixed phase and knotting in the collapsed phase.

Abstract

A system of two self and mutual interacting ring polymers, close together in space, can display several competing equilibrium phases and phase transitions. Using Monte Carlo simulations and combinatorial arguments on a corresponding lattice model, we determine three equilibrium phases, two in which the rings segregate in space and are either extended (the segregated-expanded phase) or compact (the segregated-collapsed phase). The third is a mixed phase where the rings interpenetrate. The corresponding phase boundaries are located numerically and their critical nature is discussed. Finally, by looking at the topological properties of the three phases, we show that the two rings are likely to be linked in the mixed phase and knotted in the segregated-collapsed phase.