Photo-Orientation of Liquid Crystals on Azo Dye-Containing Polymers

Abstract

In this communication, we summarise our results related to light-induced orientational phenomena at liquid crystal–polymer interfaces. We investigated photoalignment for various nematics at the interface with the photosensitive polymer layer polymethyl methacrilate functionalised with azo dye Disperse Red 1. It was found that the efficiency of photoalignment exhibits marked differences depending on the structure of the rigid core of the liquid crystal molecules. It was demonstrated that the photo-orientation process is also significantly affected by the type of mesophase in which irradiation is carried out. The observations highlight the importance of the mutual influence of the polymer and the liquid crystal in light-induced processes.

Photoaligning Polymeric Command Surfaces: Bind, or Mix?

“…It is worth comparing the results of azimuthal photoalignment obtained here on PMMA+DR1 substrates, with previous studies on a different system [20,42]. In Refs.…”

“…In Refs. [20,42], the command surface was prepared from the mixture of polyimide (PI) and azo dye Disperse Orange 3 (DO3). More precisely, the substrates were coated with a saturated solution of DO3 in polyamic acid solution, and the iridization was completed thermally.…”

“…The dynamics of the photoalignment is slower, and the photoalignment angle is smaller, when compared to the command surfaces made of polymers grafted with photochromic units-see, e.g., in Ref. [42].…”

Kinetic Study of Coprinus cinereus Peroxidase-Catalyzed Oxidation of 2,2′-Dihydroxyazobenzene

“…Recent studies have delved into the photophysical properties of azo dyes, revealing intriguing phenomena such as photoisomerization. This property is instrumental in the development of photo-responsive materials, including liquid crystal displays and light-sensitive polymers, showcasing the versatility of azo compounds in material science [5][6][7][8]. Effects such as photo-switchable and antiproliferative effects of azo compounds have also been actively investigated [9,10].…”

Photoaligning Polymeric Command Surfaces: Bind, or Mix?

“…It seems that command surfaces prepared by physical mixing the polymer with the photochromic units requires significantly higher light power for photoalignment, the dynamics of the photoalignment is slower, and is less complete (the angle of the photoalignment is less than that required by the light polarisation), when compared to the command surfaces made of polymers grafted with photochromic units − see, e.g., in Ref. [38].…”