The proper alignment of liquid crystals (LCs) is the key factor for the correct operation of all LC-based devices. There are several methods to orient liquid crystals on the bounding substrate; one of them is the use of polarized light (so called photoalignment). We provide experimental evidence that photoalignment at the nematic liquid crystal (NLC)-polymer interface cannot be simply considered as a two-dimensional process [1]. Moreover, our experiments clearly indicate that the photoaligning process does not depend on the individual properties of the NLC material and those of the interfacing polymer exclusively. The polymer and the NLC layer interact, i.e., the polymer-liquid crystal interface should be regarded as a coupled system, where the two components mutually influence each other. Due to these interactions, substantial differences have been found in the photoalignment process when the molecular structure of the NLC is systematically varied [2]. A phenomenological explanation is given for the observed differences. Furthermore, we show that the temperature induced anchoring transition also has to be taken into account for the complete description of the photoalignment mechanism.

[1] T. Tóth-Katona and I. Jánossy, J. Mol. Liq. 285, 323 (2019).

[2] A.K.R. Nassrah, I. Jánossy, and T. Tóth-Katona, J. Mol. Liq. 312, 113309 (2020).