Self-assembled periodic micro-nanostructures triggered by responses to external influences often occur in anisotropic self-assembled supramolecular soft-matter systems (such as liquid crystal (LC) systems). However, these structures are often not easily to control or even change, e.g., orderliness of the structures. A pre-built 1D periodic microgroove structure on the planar cholesteric LC cell is used to study whether it can effectively improve the large-area order of the electro-induced 2D deformation structure. Experimental results show that the 2D microgrid structure caused by the Helfrich deformation of the CLC can be effectively controlled to be ordered macroscopically by the pre-built 1D periodic microgroove structure. Furthermore, the uniformity of the microgrid size is also improved. The findings enhance the potential applicability of the well-known Helfrich deformation phenomenon and provide an example for further control of periodic micro-nanostructures in self-assembled supramolecular systems.
In this study, the bent dimers were added in the azobenzene chiral doped cholesteric liquid crystals. The photoisomerization of azo-chiral material can induce a change in pitch and eventually lead to the occurrence of Helfrich deformation. Experimental results show that the photoinduced microgrid structure can be significantly stabilized by adding bent dimers and simultaneously applying a low voltage below the threshold of electric-induced Helfrich deformation. Furthermore, the spacing of the resulting meshed microgrids can be tuned by dimer concentration or applied voltage, revealing its potential for multiparameter controllable optical diffraction devices.
With the flourish development of artificial intelligence, lasing with tailored features generated by photonic crystal lasers play a more important part in the field of optics and in potential applications such as self-control, LiDAR, telecommunications, and, holography imaging. Here, a self-steering lasing emission from a defect-mode sandwich-like structure consisting of photomechanical deformed azobenzene cholesteric liquid crystal elastomer is demonstrated. The output single-mode lasing emission can be fast steered by UV irradiation to a widely angular tuning range of approximately ±60° with an excitation threshold of Eth = 7.9 ± 0.5 μJ cm−2 per pulse. We envision that this flexible, portable and durable sandwich-like laser system with controllable lasing beam steering and mechanical robustness will open a gate for self-driving vehicle, self-sustained machines and optical devices with the core feature of photomechanical transduction.
The self-organized periodic micro/nano structure caused by the deformation of the stimulus responsive structure often occurs in anisotropic self-assembled supramolecular systems (such as cholesteric liquid crystal (CLC) systems). However, the long-distance ordering of these structures is often not easy to control. This investigation first demonstrates the manipulation ability of a 1D interference field on the macroscopic orderliness of the resulting 2D microgrid chiral structure via the firstly discovered photopolymerization-induced Helfrich deformation. A pre-built polymer layer in the early stage of photopolymerization continuously thicken to compress the helical pitch of the CLC–monomer region and then induce an internal longitudinal strain, leading to the 2D disordered microgrid structure of Helfrich deformation. A 1D laser interference field can effectively control the post-formed 2D grid microstructure to be arranged in an orderly manner in a macro-exposure area.
In this work, the thermal- and photo-reversible symmetrical deformation and structural color changed actuators based on fully-polymerized cholesteric liquid crystal (CLC) polymer beads are demonstrated. A jack-inspired soft microdevice comprising durable fully-polymerized CLC beads by the stand-alone and free of extraction technique is demonstrated to have the unique photo-responsive capabilities of lifting substantially heavy objects and photochromatism via light-triggered symmetric volume expansion of the CLC beads. The desired symmetrical volume expansion with photochromatic property is realized by decreasing the degree of the order parameter, which is caused by the reorientation of the LC director. Such dynamic manipulation of anisotropic geometric deformation of soft materials offer promising infinite possibilities for the applications of smart devices.
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