Solvation and phase separation in ABA block copolymers

摘要

AbstractA conceptual scheme is presented for classifying the phase behavior of ABA block copolymers and solvents. The effect of solvent fraction ϕSonmicrophaseseparation is described for macroscopically homogeneous systems, but more attention is focused on the limits of solubility. A “miscibility map” is developed in terms of solubility parameters δA, δB, and δSand used to define regions ofmacrophaseseparation, complete miscibility, and partial miscibility. Combined with known triblock molecular structure, the miscibility map can be used to predict the character of solvated systems and guide the selection of solvents for special purposes. A survey of reports in the literature shows qualitative consistency with this treatment. New observations are reported on solvation of a polystyrene–polybutadiene–polystyrene polymer in numerous solvents; these are used to infer microstructural information and define the miscibility map more re