Smectic Defect Engineering Enabled by Programmable Photoalignment

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. A strategy for flexible defect engineering in liquid crystals is proposed and demonstrated via preprogramming alignment conditions. Smectic defect walls are guided in a predictable manner based on the deflecting, bending, and splaying of oily streaks. Electric stimuli further endow the defect array with tunability and rotatability. This defect architecture supplies a platform for upgraded microfabrication and advanced photonic applications.