Highly Conducting Lyotropic Liquid Crystalline Mesophases Of Pluronics (P65, P85, P103, And P123) And Hydrated Lithium Salts (Licl And Lino3)

Demand for ionically conducting materials, as membranes and electrodes, is one of the driving forces of current research in chemistry, physics, and engineering. The lithium ion is a key element of these materials, and its assembly into nanostructures and mesophases is important for the membrane and electrode technologies. In this investigation, we show that hydrated lithium salts (such as LiCl center dot xH(2)O and LiNO3 center dot xH(2)O, x is as low as 1.5 and 3.0, respectively) and pluronics (triblock copolymer such as PX where Xis 65, 85, 103, and 123) form lyotropic liquid crystalline mesophases (LLCM), denoted as LiY center dot xH(2)O-PX-n (Y is Cl- or NO3-, and n is the salt/PX mole ratio). The structure of the mesophase is hexagonal over a broad salt concentration and transforms to a cubic mesophase and then to disordered gel phase with an increasing salt content of the mixtures. The mesophases are unstable at low salt contents and undergo a phase separation into pure pluronics and salt-rich LLCMs. The salt content of the ordered mesophase can be as high as 30 mole ratio for each pluronic, which is a record high for any known salted phases. The mesophases also display high ac ionic conductivities, reaching up to 21 mS/cm at room temperature (RT), and are sensitive to the water content. These mesophases can be useful as ion-conducting membranes and can be used as media for the synthesis of lithium-containing nanoporous materials.