Smectic a1 ↔ a2 transition of n c-60.8 : a two-dimensional phase separation of the molecular endgroups

2014 The smectic A1 ~ A2 phase transition of a one-component liquid crystalline system was studied with X-ray diffraction. The smectogen used was a polar but symmetrical smectogen, namely the 4-cyanohexyloxybenzylidene-4’-octylaniline. The intensities of the Bragg reflections were measured as a function of temperature. The experimental data were analysed according to a structural model describing the location of the cyano and methyl endgroups of the molecules at the surface of the smectic layers. The A1 ~ A2 transition was then interpreted in terms of a twodimensional phase separation of the endgroups. J. Phys. France 50 (1989) 375-386 ler FÉVRIER 1989,