The structural evolution of films of the liquid crystal mixture mx5112 in the Sm-A and Sm-C* phases has been studied using X-ray scattering techniques. Liquid crystal (LC) films spread on glass substrates with relief grating of 10µm period are subjected to competing boundary conditions on opposite sides. On one side, the LC-air interface imposes a homeotropic boundary condition while on the other the glass substrate with grating generally imposes a homogeneous boundary condition. Near room temperature, the smectic layer normal is oriented parallel to the grating lines on the substrate. The measured srnectic layer spacing reveals oscillations between a Sm-C* and a Sm-A like structures which depend on the film thickness as well as the distance from LC-air interface and is attributable to the difference in the molecular tilt imposed by a. the air-LC interface; b. the substrate; and c. the gratings' internal walls.
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals
Martínez-Miranda, L. J.; Shi, Yushan; Kumar, Satyendra (1999). Time Evolution of the Structure of Confined SmC* Films. Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals 326 41-48. doi: 10.1080/10587259908025403. Retrieved from https://oaks.kent.edu/article/time-evolution-structure-confined-smc-films