Evaluation of mesomorphic and thermal stabilities for terminal epoxy liquid crystals

Two series of terminal epoxy compounds, PmOBC (m = 1, 2, 3, 4) and P1OBEn (n = 6, 8, 10, 12), were synthesized for investigating the effect of epoxidation on mesomorphic and thermal stabilities. Molecular polarization and configuration obtained by DFT calculations can provide theoretical perspective. In addition, thermal stability is evaluated by the combination of DSC, TGA, and 1H NMR. Compared with the corresponding alkenyl compounds, epoxidation reduces the molecular dipole moment and increase the molecular steric effect, which is not conducive to the formation of LC phases, but the reduced intramolecular energy may be helpful to improve thermal stability. Therefore, these terminal epoxy LCs are very promising for application in display devices requiring extremely high-temperature environments.