Construction of Polymer-Stabilized Automatic MultiDomain Vertical Molecular Alignment Layers with Pretilt Angles by Photopolymerizing Dendritic Monomers under Electric Fields

Abstract

The synthesized itaconic acid-based dendritic amphiphile (Ita3C 12 ) monomers and the methacryl polyhedral oligomeric silsesquioxane (MAPOSS) cross-linkers were directly introduced for the construction of automatic vertical alignment (auto-VA) layers in the host nematic liquid crystal (NLC) medium. The auto-VA layer can be stabilized by irradiating UV light. For the automatic fabrication of a polymer-stabilized multidomain VA (PS auto-MDVA) layer with a pretilt angle, Ita3C 12 and MAPOSS were photopolymerized under the electric field by irradiating UV light on the multidomain electrode cell. Mainly because of the pretilted NLC at zero voltage, the electro-optic properties of the PS auto-MDVA cell were dramatically improved. From the morphological observations combined with surface chemical analyses, it was found that various sizes of protrusions on the solid substrates were automatically constructed by the two-step mechanisms. We demonstrated the PS auto-MDVA cell with the enhancement of electro-optic properties as a single-step process and investigated how the protrusions were automatically developed during the polymer stabilization.

Highly Stable, Pretilted Homeotropic Alignment of Liquid Crystals Enabled by In Situ Self-Assembled, Dual-Wavelength Photoalignment

“…The random distribution of RM aggregates corresponds to the morphological evidence of a factor responsible for homeotropic alignment as it breaks the boundary symmetry conditions of LCs. Morphological observations imply that the nature of alignment formation could be similar to SAMs or nanoparticle doping systems that exert homeotropic alignment of LCs 52,53 . The low RM257 concentration case could not provide much information regarding the anisotropic nature of RM stabilization layer or LC director orientation.…”

Light responsive liquid crystal soft matters: structures, properties, and applications

“…The control of molecular alignment is one of the important technologies for high-performance optical devices [49]. Particularly in the LCD industries, the orientation of anisotropic molecules has been achieved by rubbing the polymer-based film [50]. The polyimides have been widely used because they exhibit strong anchoring interactions with the LC molecules and mechanical stability onto the substrates [51].…”

Nematic Structures under Conical Anchoring at Various Director Tilt Angles Specified by Polymethacrylate Compositions

“…The director tilt angle can be controlled by selecting the type and concentration of surfactants [ 16 ], polymers, their mixtures, or processing technology. For instance, the tilt angle varies in the wide range by the mixture composition of two polymers specifying homeotropic and tangential boundary conditions [ 17 , 18 , 19 , 20 , 21 ], depth and time of rubbing of orienting polymer films [ 18 , 19 , 22 , 23 , 24 ], freezing of the formed director orientation using photo-cured polymer dissolved in LC [ 20 , 22 , 25 , 26 , 27 , 28 , 29 ], the time and temperature of annealing of polyamide film [ 19 , 21 , 24 , 30 ], etc. In most cases, when assigning the director tilt angle, the homogeneous azimuthal orientation is formed due to the rubbing of both LC cell substrates.…”