Remote-controllable and encryptable smart glasses: a photoresponsive azobenzene molecular commander determines the molecular alignments of liquid crystal soldiers

Self-Assembled and Polymerized Hierarchical Nanostructure Films of Cyanostilbene-Based Reactive AIEgens for Smart Chemosensors

For the development of acid-responsive advanced fluorescent films with a 2D nanostructure, a pyridyl cyanostilbene-based AIEgen (PCRM) is newly synthesized. The synthesized PCRM exhibits aggregation-induced emission (AIE) and responds reversibly to acid and base stimuli. To fabricate the nanoporous polymer-stabilized film, PCRM and 4-(octyloxy)benzoic acid (8OB) are complexed in a 1:1 ratio through hydrogen bonding. The PCRM-8OB complex with a smectic mesophase is uniaxially oriented at first and photopolymerized with a crosslinker. By subsequently removing 8OB in an alkaline solution, nanopores are generated in the self-assembled and polymerized hierarchical 2D nanostructure film. The prepared nanoporous fluorescent films exhibit not only the reversible response to acid and base stimuli but also mechanical and chemical robustness. Since the nanoporous fluorescent films have different sensitivities to trifluoroacetic acid (TFA) depending on the molecular orientation in the film, advanced acid vapor sensors that can display the risk level according to the concentration of TFA are demonstrated. Reactive AIEgens-based hierarchical nanostructure films with nanopores fabricated by a subsequent process of self-assembly, polymerization, and etching can open a new door for the development of advanced chemosensors.

Encryptable Electrochromic Smart Windows: Uniaxially Oriented and Polymerized Hierarchical Nanostructures Constructed by Self-Assembly of Tetrathiafulvalene-Based Reactive Mesogens

Tetrathiafulvalene (TTF)-based reactive mesogens (TTF-E and TTF-T) are synthesized, self-assembled, uniaxially oriented, and polymerized for the development of encryptable electrochromic smart windows. Electrochemical and spectroscopic experiments prove that the self-assembled TTF mixture (TTFM, TTF-E:TTF-T = 1:1) can reversibly switch the absorption wavelength of the TTF chromophore according to the redox reactions. Based on the identification of the phase transition and crystallographic structure, uniaxially oriented hierarchical nanostructures are easily constructed on the macroscopic area by simple coating and a self-assembly process. Subsequent polymerization of hierarchical nanostructures of TTFM significantly enhances thermal and mechanical stabilities and makes it possible for them to be fabricated as an electrochromic device. The angularly dependent correlation between the anisotropy of mesogens and the linearly polarized light allow us to demonstrate TTFM as smart windows capable of various optical security applications, including privacy protection and information encryption.

Smart Nematic Liquid Crystal Polymers for Micromachining Advances

The miniaturization of tools is an important step in human evolution to create faster devices as well as precise micromachines. Studies around this topic have allowed the creation of small-scale objects capable of a wide range of deformation to achieve complex tasks. Molecular arrangements have been investigated through liquid crystal polymer (LCP) to program such a movement. Smart polymers and hereby liquid crystal matrices are materials of interest for their easy structuration properties and their response to external stimuli. However, up until very recently, their employment at the microscale was mainly limited to 2D structuration. Among the numerous issues, one concerns the ability to 3D structure the material while controlling the molecular orientation during the polymerization process. This review aims to report recent efforts focused on the microstructuration of LCP, in particular those dealing with 3D microfabrication via two-photon polymerization (TPP). Indeed, the latter has revolutionized the production of 3D complex micro-objects and is nowadays recognized as the gold standard for 3D micro-printing. After a short introduction highlighting the interest in micromachines, some basic principles of liquid crystals are recalled from the molecular aspect to their implementation. Finally, the possibilities offered by TPP as well as the way to monitor the motion into the fabricated microrobots are highlighted.