Phase behaviour of a thermotropic cubic mesogen of 1,2-bis(4′-n-hexyloxybenzoyl)hydrazine under pressure

Abstract

The phase behaviour of the thermotropic cubic mesogen 1,2-bis(4′-n-hexyloxybenzoyl)hydrazine [BABH(6)] was investigated under pressure up to about 55 MPa using a polarising optical microscope equipped with a high-pressure optical cell. BABH(6) shows the crystal (Cr)–cubic (Cub)–isotropic liquid (I) phase transition at ambient pressure on heating. The smectic C (SmC) phase was induced above 32 MPa, showing the unusual phase sequence of Cr–Cub–SmC–I, similar to those in BABH(n) (n = 8–10). The boundary between the Cub and SmC phases exhibited a negative slope dT/dP of about –1.0 ºC MPa⁻¹.

Keywords:

• thermotropic cubic mesogen
• BABH
• POM
• pressure
• cubic phase

Funding

This work was partly supported by a Grant-in-Aid for Scientific Research (C) 25410091 from the Japan Society for the Promotion of Science (JSPS); by a Grant-in-Aid for Scientific Research on Priority Areas [446/19022012] from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) (for S.K.); by a Grant-in-Aid for Scientific Research on Priority Areas [463/19031002] from MEXT; and by a Grant-in-Aid for Scientific Research on (B) 22350056 from JSPS (for K.S.).