Dual wavelength in situ photoalignment for stable planar alignment of nematic liquid crystals

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

“…The LPVL and UV-light treatment processes are therefore referred as dual-wavelength photoalignment. The RM polymerization is initiated by a photoinitiator used in trace amounts, upon unpolarized UV-light (λ2) irradiation at room temperature [43][44][45][46] . Stabilization of LC alignment by RM polymerization results in the formation of a thin polymer layer on top of the composite layer of SAA and azo-dye molecules, as shown in Figure 1d.…”

“…Stabilization of LC alignment by RM polymerization results in the formation of a thin polymer layer on top of the composite layer of SAA and azo-dye molecules, as shown in Figure 1d. The RM stabilization layer seizes the freedom of azo-dyes reorientation capability influenced by reversible photoisomerization process 46,47 . Here onwards, the new RM layer commands the LC alignment and endures irreversible LC orientation along specific direction.…”

“…The RM polymerization is initiated by a photoinitiator used in trace amounts upon unpolarized UV-light (λ 2 ) irradiation at room temperature. − Stabilization of LC alignment by RM polymerization results in the formation of a thin polymer layer on top of the composite layer of SAA and azo-dye molecules, as shown in Figure d. The RM stabilization layer seizes the freedom of azo dyes’ reorientation capability influenced by the reversible photoisomerization process. , Here onward, the new RM layer commands the LC alignment and endures irreversible LC orientation along a specific direction. The formed RM layer over the composite layer of additives is represented in light brown color, as shown below Figure d.…”

Photoinduced Reorientation and Photofunctional Control of Liquid Crystalline Copolymers with in Situ-Formed N-Benzylideneaniline Derivative Side Groups

“…Photoalignment of polymeric films is utilized to fabricate optical and display devices, where light exposure regulates the molecular reorientation direction of the material. − Conventionally, a command surface technique using thin photoalignment layers is applied to uniaxial liquid crystal (LC) alignment to fabricate LC displays and birefringent and optical devices combined with polymerizable LCs. − By contrast, the use of photoalignable LC polymers can enable direct fabrication of a photoinduced molecularly oriented structure of the polymeric film by means of linearly polarized (LP) light exposure and, in some cases, thermally stimulated self-organization. ,− …”

Shining Light on Liquid Crystal Polymer Networks: Preparing, Reconfiguring, and Driving Soft Actuators

“…Regarding the photoalignement of reactive mesogens through a surface alignment layer, it is a noncontact method (without surface rubbing) that is effective for creating complex LC director profiles in the resulting LCN, such as homogeneous, homeotropic, twisted and splay director fields, and the corresponding diverse shape transformations upon an order–disorder phase transition . In principle, photoinduced molecular orientation of the alignment surfaces, which are typically photosensitive polymers containing covalently‐bonded chromophores such as azobenzene, cinnamate, chalcone, and coumarin moieties, is a result of the selective responsiveness of the dichroic chromophores to linearly polarized light .…”