Dresden 2020 – wissenschaftliches Programm
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PLV II: Plenarvortrag
Montag, 16. März 2020, 08:30–09:15, HSZ 01
Bicontinuous Structures in Charged Polymer Blends — •Timothy Lodge — University of Minnesota, Minneapolis, MN, USA
Nanostructured materials with co-continuous structures, in which each discrete domain is independently interconnected, can simultaneously achieve orthogonal properties such as rapid ion transport and excellent mechanical strength. Potential applications include porous membranes, fuel cells, and rechargeable metal batteries. A promising route involves blending an AB diblock copolymer with the constituent A and B homopolymers, leading to a disordered bicontinuous microemulsion (BuE) state. We have shown that charge-free ternary AB/A/B polymer blends universally self-assemble into the thermodynamically stable BuE phase, albeit with carefully designed molecular weights and compositions. The BuE is found in a narrow window near the location of an isotropic Lifshitz point predicted by mean-field theory, and is presumably stabilized by fluctuations. The interesting question that arises is whether this phase can also be accessed in blends containing charge, where in general the intermolecular interactions are stronger and more long-ranged. We are exploring this issue in two cases: an AB/A/B ternary system with added salt, and an AB/A/B system in which one of the polymers is ionomeric. Surprisingly, in both cases an even wider BuE channel occurs for symmetric compositions (equal volumes of A and B), despite huge asymmetries in the binary blend phase diagram for the same system.