Liquid Crystal Transitions

Liquid crystals are substances that exhibit a phase of matter that has properties somewhere between those of a conventional liquid and those of a solid crystal. For instance, a liquid crystal (LC-Liquid crystal) may flow like a liquid, but have the molecules in the liquid arranged and/or oriented in a crystal-like way.

As an example of such phase transitions in liquid crystal samples, the measurement on para-Azoxyanisole is illustrated. Here, different phase changes are clearly pronounced, such as the crystalline to nematic phase change at 118°C peak temperature as well as the nematic to isotropic melt change at 134°C peak temperature.

Differential scanning calorimetry (DSC) is a useful tool which complements optical methods in the study of liquid crystal phase transitions. It is utilized in determining the heat supplied or extracted during a process such as phase transition.

Sample: para-Azoxyanisole, Al crucibles, 5 K/min HR, nitrogen atmosphere, Sample mass 2.5 mg

Related Methods