Phase Behavior of Salt Doped A/B/A-B Ternary Polymer Blends

The phase prism of a pseudoternary polymer blend system containing low molar mass poly(ethylene oxide) (PEO) and polystyrene (PS) homopolymers, a PS−PEO block copolymer (SEO), and lithium bis(trifluoromethane)sulfonamide (LiTFSI) is constructed. The addition of salt increases the segregation strength, and thus causes both macroscopic and microscopic phase separation. The phase behavior of the ternary system is studied in detail, including isothermal slices at different temperatures and isopleths with different phi_PEO/phi_h ratios. Also, a bicontinuous microemulsion (BμE) channel is located, and the structure as a function of salt concentration and temperature is investigated. Moreover, the congruency condition near the BμE channel will be discussed. This work may serve as a benchmark for experimental design of polyelectrolyte systems with tunable ionic conductivity and high mechanical modulus and help understand the physics underlying the structure and dynamics of ion-containing A/B/A-B ternary blends.