Phase Sequence, Kinetics of Crystallization and Molecular Dynamics of the Chiral Liquid Crystalline Compound Forming a Hexatic Smectic Glass

The vitrification of the antiferroelectric hexatic smectic X-A* phase and cold crystallization are reported for (S)-4 '-(1-methylheptylcarbonyl)biphenyl-4-yl 4-[5-(2,2,3,3,4,4,4-heptafluorobutoxy) heptyl-1-oxy]benzoate. The kinetics of isothermal cold crystallization and melt crystallization are investigated, revealing that both are controlled mainly by diffusion, as indicated by decrease in the characteristic crystallization time with increasing temperature of crystallization, with an activation energy of 114 kJ/mol. A weak relaxation process is detected in a crystal phase, with an activation energy of 38 kJ/mol, implying the conformationally disordered crystal phase. The estimated fragility parameter of the investigated glass former is equal to 94.5, which indicates rather high fragility.

Automated summary

The vitrification and cold crystallization of the antiferroelectric hexatic smectic X-A* phase for (S)-4 '-(1-methylheptylcarbonyl)biphenyl-4-yl 4-[5-(2,2,3,3,4,4,4-heptafluorobutoxy) heptyl-1-oxy]benzoate are investigated. It is found that the kinetics of both isothermal cold crystallization and melt crystallization are mainly controlled by diffusion, with an activation energy of 114 kJ/mol. A weak relaxation process is observed in the crystal phase, implying the presence of a conformationally disordered crystal phase. The fragility parameter of the glass former is estimated to be 94.5, indicating a relatively high fragility.