Optical switching of bent-core liquid crystals with azocinnamoyl units

Cmok, Luka (author), Mattiazzi, Simon (author), Drevenšek Olenik, Irena (author), Sebastián Ugarteche, Nerea (author), Gak Simić, Kristina (author), Trišović, Nemanja (author), Vilfan, Mojca (author)

We report on observations of optical switching in bent-core liquid crystals possessing azocinnamoyl groups in both elongated side arms. UV-activated switching was observed in two of the synthesised materials, both of which were studied optically and with dielectric spectroscopy. Polarising microscopy was used to measure the changes in optical transmittance, and while no illumination effect was seen in the nematic phase, visible changes were observed in the smectic phase, most pronounced in the close vicinity of the smectic to nematic-phase transition. Switching dynamics was characterised, and we found that the average switching time varies strongly with temperature. The relaxation process is faster (below 200 ms) and exhibits no significant temperature dependence. Dielectric measurements have shown that the observed smectic C phases were not polar with the molecules possessing a rather small electric dipole moment. Upon illumination, small differences in the dielectric permittivity were observed only in the smectic phase, suggesting that the illumination effect can be attributed to changes in the molecular conformational and orientational order.

• Language: English
• Keywords: bent-core liquid crystals, photo-switching, azocinnamoyl group, optical switching, switching dynamics
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: Str. 1599–1607
• Numbering: Vol. 50, no. 7/10
• PID: 20.500.12556/RUL-152840
• UDC: 532
• ISSN on article: 1366-5855
• DOI: 10.1080/02678292.2023.2179120
• COBISS.SI-ID: 142935299
• Publication date in RUL: 08.12.2023

Record is a part of a journal

• Title: Liquid crystals
• Shortened title: Liq. cryst.
• Publisher: Taylor & Francis
• ISSN: 1366-5855
• COBISS.SI-ID: 18299943

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.

Secondary language

• Language: Slovenian
• Keywords: tekoči kristali z upognjeno sredico, fotopreklapljanje, azocinamat, optično preklapljanje, dinamika preklapljanja, tekoči kristali