Coacervation in dilute charged polymer solution

Coacervate is dispersed droplet of dense phase, liquid-liquid phase separation of oppositely charged polymer in a mixture of polymer solution. In this study, phase behavior of oppositely charged polymers were investigated as functions of charged polymer length (15,30,45,60) and concentration of counterions in dilute polymer solution limit. Two types of linear polymer chains, which is charged in all positive and all negative, exist in the same number with different concentration of counterions in the simulation box. We observed coacervation and dispersion of polymers upon a change in concentration of counterions. Also, depending on the chain length of the charged polymer, the concentration of counterions at which dispersion occurs is slightly different. Molecular dynamics simulations suggested the dispersion of charged polymers according to counterions, which satisfy the local electrical neutrality of charged polymers. We can observe coacervate in dilute solution limit when the counterion's local influence is small.