R. Ulrich

Microphase Separation in Poly(isoprene-b-ethylene oxide) Diblock Copolymer Melts. I. Phase State and Kinetics of the Order-to-Order Transitions

The phase state and the kinetics of the order-to-order transitions have been studied in a series of poly(isoprene-b-ethylene oxide) (PI-PEO) diblock copolymers with a PI volume fraction in the range 0.25<fPI<0.92, using small angle x-ray scattering (SAXS), and rheology. The mean-field theory (MFT) structure factor is used to describe the SAXS profiles in the disordered phase and to extract the temperature dependence of the interaction parameter χ(T). In general, an agreement is found with the phase diagram proposed by an extended MFT, except at fPI=0.61 where the following sequence of phases was found: Lc→Hex→Gyroid→Dis (Lc is the crystalline lamellar phase, Hex signifies hexagonally packed cylinders, Gyroid is the bicontinuous cubic network with the Ia3d symmetry, and Dis is the disordered phase). We found that crystallization disrupts the amorphous ordered morphologies and imposes a layered structure (Lc). The study of the kinetics of the Hex to Lc and the Hex to Gyroid transitions is facilitated by th...

Solid Hybrid Polymer Electrolyte Networks: Nano-Structurable Materials for Lithium Batteries

Remarkably high lithium transference numbers and excellent mechanical strength characterize the solid hybrid polymer (SHyP) network presented here. The material (see Figure) allows block copolymer processing into nanometer-scale plates and rods, paving the way to the fabrication of lithium-conducting cables and eventually solid-state electrochemical devices of sizes down to 10 nm.