Self-assembly of polyelectrolyte diblock copolymers within mixtures of monovalent and multivalent counterions
In this study, the self-assembly behavior of polyelectrolyte (PE) diblock copolymers in solutions containing mixtures of monovalent and multivalent counterions is investigated using molecular dynamics simulation. The properties of the assembled micelles and counterion condensations at different fractions of charge of multivalent ion are discussed. The bridging effect of multivalent ions induces electrostatic correlations of the PE chains, leading to the fusion of large micelles and the formation of bulky aggregates. Notably, lamellar and well-organized face-centered cubic (FCC) arrangements of the assembled micelles are observed in the mixture of monovalent and trivalent ions. At large fractions of multivalent ions, cylindrical and lamellar precipitates composed of the assembled micelles are formed owing to the inter-connecting coronas. Mixtures of monovalent and multivalent counterions allow regulation of the electrostatic interactions and tuning of the properties in assembled micelles.