Collapse Transition of Cyclic Homopolymers and Block Copolymers

In order to determine the structure of cyclic homopolymer and multiblock copolymer polymers (rings) at various solvent qualities (temperatures), an idealized model of macromolecules is developed and studied. All atomic details are suppressed and chains are represented as a sequence of identical beads embedded in a square lattice. A simple square-well potential is used for polymer-polymer interactions in order to mimic the influence of nonselective solvent. An efficient Monte Carlo sampling algorithm using local and nonlocal changes of chain conformation as well as the Replica Exchange technique is used to sample the conformational space. Simulation results concerning the structure of globules formed at low temperature are discussed and compared with theoretical predictions. The influence of the arrangements of blocks in the chain on its structure in different temperatures is shown.