Thermodynamic study for the role of functional group on the honey-comb pattern interaction between CNT and E5CN7 nematic liquid crystal

A carboxyl functionalized single-walled carbon nanotube (CNT-COOH) was doped to eutectic E5CN7 mixtures of pentylcyanobiphenyl (5CB) and heptylcyanobiphenyl (7CB) liquid crystals to investigate the phase transition temperatures and the thermodynamic behaviors. The thermal investigations showed that the nematic (N) - isotropic (I) phase transition temperature was decreased linearly as a function of CNT-COOH concentration at both the heating scan rate and the cooling scan rate. The honey-comb pattern or the anchoring effect contributes greatly to the N-I phase transition. When the CNT is functionalized, its aggregation is diminished. However, the anchoring effect increases after the functionalization of the CNT. In comparison with non-functionalized CNT, the phase transition temperature is decreased significantly by the functionalized CNT doped to LCs because of the increasing honey-comb pattern and the hydrogen bonding between the CNT and the E5CN7 LCs.