ELFT HÍRADÓ

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SZFI SeminarTóth-Katona TiborWigner RCP SZFIPhotoalignment at the nematic 
liquid crystal – polymer interface: reorientation in 3D &  the role of the 
liquid crystalline molecular structureTuesday, 15 September 2020, 10:00, 
video conference, https://letsmeet.wigner.hu/szeminariumThe 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).  Minden 
érdeklődőt szívesen látunk! - Everyone is welcome to attend.Róbert 
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