Oriented glass states formed by ionic liquid–liquid crystals

Thermotropic liquid crystalline systems containing an ammonium unit formed glassy smectic A, smectic A, and ionic liquid phases. In the smectic A phase, a homeotropic alignment occurred spontaneously due to physical adsorption of ionic units and strong interactions between nitroazobenzene mesogenic groups. The homeotropic alignment in the smectic A phase remained unaltered in the glass state (glassy smectic A phase) because the ionic interactions exhibit an effect that is equivalent to a polymer backbone of side-chain liquid crystal polymers during the formation of the oriented glass state. The glass transition of the ionic liquid crystal was accurately evaluated by DSC measurement. These experimental results reveal that oriented films with a monodomain structure can be obtained by the physical adsorption and the formation of the glassy smectic A phase, which is caused by the ionic interactions.