Thermal characterisation of binary mixture of some supramolecular liquid crystals

The thermal characterisation of binary mixture formed from hydrogen-bonded supramolecular liquid crystals 4-hexylbenzoic acid (6BA) and 4-octyloxybenzoic acid (8OBA) was investigated by differential scanning calorimetry (DSC) and phases identified by polarised optic microscopy (POM). The phase diagram of the mixture was obtained from theoretical calculations, and binary mixture with a maximum nematic range according to the phase diagram was produced. The DSC and POM results clearly indicate that the produced liquid crystal mixture displays liquid crystalline properties, and the nematic range of 6BA/8OBA eutectic mixture is wider than the nematic ranges of both liquid crystals 6BA and 8OBA. Also with increasing the heating rate from 5 to 20 A degrees C min(-1), the phase transitions occur in a shorter time. As a result, the 6BA/8OBA mixture does not loss its liquid crystalline properties against sudden temperature changes.