Observing Pre-Crystalline and Post-Crystalline Phase Transitions of 6OCB and 10OCB Liquid Crystals with 5 °C/min Ramp Rate Using DSC

This paper focuses on the unique behavior of 6OCB and 10OCB Liquid Crystals (LC) compared to 8OCB liquid crystal from the n-octyloxycyanobiphenyl (nOCB) thermotropic LC family. Three LCs from nOCB, 6OCB, 8OCB, and 10OCB were studied using the Differential Scanning Calorimetric (DSC) technique at a 5 °C/min ramp rate for heating and cooling. The DSC data was then analyzed in detail using Logger Pro. It is found that 6OCB is the youngest and lightest member of nOCB and shows a new state of pre-crystalline on heating, whereas 10OCB is the oldest and heaviest member of nOCB that shows a new state of post-crystalline on heating, when compared with 8OCB LC, whereas 8OCB shows nothing like that. These two new states make these LCs, 6OCB and 10OCB, very interesting material for research, showing bigger transition peaks, remaining in their distinct phases for a longer time, and having higher thermal energy occurring in these LCs. These novel states of matter make these LCs important in the research and application field of LCs. These unique states of 6OCB and 10OCB are explained with a predicted model of molecular alignment with the existence of a partially crystalline state as the Pre-Crystalline state in 6OCB, as it has the smallest tail size. At the same time, two energy levels are predicted in 10OCB LC: Crystalline and Post Crystalline states, as it has the largest tail in its molecular structure. The presence of these unique states in 6OCB and 10OCB makes them more stable with wide and longer transition peaks, and can be useful considering them in Smart devices where a wide temperature range is required to manufacture them as Liquid Crystal Display devices (LCDs) or Smart watches or Smart Laptops.