Host-guest molecular interactions in the phase transition of liquid crystals

ABSTRACT

Phase transition dynamics of liquid crystal (LC) was measured by the heterodyne transient grating (HD-TG) method to clarify the difference between the photochemical and photothermal phase transitions. The phase transition was induced by the photo-excitation of different guest dyes doped in the host liquid crystals; azobenzene and solvent red were used as photochemical and photothermal dyes as guest dyes. The photochemical phase transition was partly induced even at much lower temperature than the nematic – isotropic phase transition temperature (T_NI) and the region was gradually increased as the temperature, while photothermal phase transition was induced in the whole area just when reaching T_NI. Furthermore, the anisotropic re-alignment of molecules was observed in the phase recovery process.

KEYWORDS:

• Phase transition
• photoisomerization
• azobenzene

Funding

This research work was supported by the Institute of Science and Engineering, Chuo University.