Smectic Defect Engineering Enabled by Programmable Photoalignment

Abstract

Topological defects are vital for tailoring soft matter properties and inspiring remarkable applications. Arbitrary guiding and dynamic tuning of director distributions are highly pursued in defect engineering of liquid crystals. Till now, the orientation control of smectic defect walls remains a challenge. Here, photoalignment is adopted to preset the surface anchoring in order to guide smectic oily streaks. Flexible defect engineering such as deflecting, bending, and splaying is demonstrated. Based on their combination, more complicated defect arrays are realized in a predictable manner. After electric stimuli involved, new functions of tunability and rotatability are unlocked. This work brings new insights to soft matter architectures, and will upgrade the existing micromachines, nanoparticle manipulations and advanced photonic applications.

Monodomain Liquid Crystals of Two-Dimensional Sheets by Boundary-Free Sheargraphy

“…The achieved MDLCs exhibit centimeter-scale continuity and regularity. Compared with other patterning methods, such as photoalignment [ 40 , 41 ], electromagnetic fields [ 7 , 13 ], and freeze casting [ 34 , 35 ], our method shows merits of high accuracy and simple equipment request, arbitrariness, and wide compatibility for two-dimensional colloids. High accuracy (2 µm) of boundary-free shearing fields, lower than the size of single GO sheet (35 µm), allows the construction of monodomain textures with high sheet ordering.…”

Role of Stimuli on Liquid Crystalline Defects: From Defect Engineering to Switchable Functional Materials

“…Ok et al [44] reported the multi-rubbing induced spatial arrangement of TFCDs, which was enabled by a tendency to maintain organization in the N phase once transitioned to the SmA phase. Sharing the function of guiding molecular orientation with the rubbing method, a photo-alignment technique has become popular [45][46][47][48][49]. It can overcome the drawbacks of the rubbing, including the mechanical damage and electrostatic charges.…”

Photo‐Actuated Chiral Smectic Superstructures

“…The stimuli-responsiveness Supporting Information). [18] The LCs adjacent to the SD1 layer tend to follow the alignment, while the homeotropic anchoring from the LC/air interface forces the parallel layers to periodically bend along the alignment direction (x axis) (Figure 1a). Therefore, a 1D OS grating with a vector along the x axis arises.…”

“…[26] Since photoalignment is adopted, surface mechanical damage and residual debris are highly suppressed, and arbitrarily patterned OSs are reasonably expected. [18] Considering the OSs can capture and orientate nanoparticles as scaffolds, photo-actuation further facilitates the particle transportation with programmable trajectories. The method of light stimulation exhibits the advantages of remote control and temporal/spatial resolution.…”