We investigate the variation of the self-assembly behavior of block copolymer upon the addition of dissolved salts. A minimal model that captures the effects of solvation free energy and electrostatics in dielectrically heterogeneous medium is developed, in which the typical assumption that ions are bound to the conductive species is discarded. The phase diagrams at varying salt concentrations and average dielectric permittivities are presented, revealing the competition between two distinct types of morphological behaviors, one dominated by ionic solvation, and another by the translational entropy of ions. The "chimney" behavior reported in literature is shown to be caused by the solvation of ions. Comparison suggests that most experimentally realistic systems fall within the solvation regime.

Competition of solvation and entropic effects in ion-containing block polymers

2019 Spring National Meeting

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