Responsive Photonic Liquid Crystalline Flakes Produced by Ultrasonication

Abstract

Responsive materials that alter their color in response to environmental changes can be used as optical sensors. Chiral nematic liquid crystals are photonic materials that selectively reflect specific wavelengths of light and have been made environmentally responsive. Herein, the use of ultrasonication of responsive cholesteric liquid‐crystal network films to form structurally colored flakes that demonstrate color changes when moved from an aqueous to dry environment and back again is demonstrated, which suggests a scalable technique to form quantities of responsive particles that could conceivably be embedded in permeable hosts to allow the optical detection of humidity or certain chemical species.

Hydrogen-Bonded Supramolecular Liquid Crystal Polymers: Smart Materials with Stimuli-Responsive, Self-Healing, and Recyclable Properties

“…As a result, LC polymers have emerged as promising smart, functional materials due to their stimuli-responsive anisotropic properties and control over the nanostructure by supramolecular organization. 5 − 9 Exciting advancements in polymeric LC materials have highlighted the potential of these materials in various applications such as soft robotics, 10 , 11 smart textiles, 12 , 13 deployable soft actuating devices, 14 , 15 adsorbents, 16 responsive pigments, 17 and sensors. 18 − 22 …”

“…As a result, LC polymers have emerged as promising smart, functional materials due to their stimuli-responsive anisotropic properties and control over the nanostructure by supramolecular organization. 5−9 Exciting advancements in polymeric LC materials have highlighted the potential of these materials in various applications such as soft robotics, 10,11 smart textiles, 12,13 deployable soft actuating devices, 14,15 adsorbents, 16 responsive pigments, 17 and sensors. 18−22 Hydrogen-bonding interactions are valuable for controlling the supramolecular organization in LC materials and enhancing the stability of polymers and/or as the active trigger endowing the materials with responsive behaviors.…”

“…The self-assembly and molecular order of liquid crystals (LC) are attractive for fabricating stimuli-responsive materials where changes in nanostructure will alter the properties of the material such as shape, color, or porosity. As a result, LC polymers have emerged as promising smart, functional materials due to their stimuli-responsive anisotropic properties and control over the nanostructure by supramolecular organization. − Exciting advancements in polymeric LC materials have highlighted the potential of these materials in various applications such as soft robotics, , smart textiles, , deployable soft actuating devices, , adsorbents, responsive pigments, and sensors. − …”

4D Printing of Liquid Crystals: What's Right for Me?

“…A slightly different approach toward incorporating densely crosslinked LCNs in an FFF procedure was demonstrated by using stimuli-responsive LC network flakes as dopant in conventional 3D printing polymer filament. [246] However, in this first report the flake response was not maintained after printing as a result of the humidity response of the LCN flake dopant being compromised by the barrier properties of the host polymer. Finding or developing more suitable water-permeable host polymers, or a new LCN formulation that works in this confined environment would open up a myriad of possibilities, given the widespread use of FFF printers and the current boom in filament material development.…”

Recent advances in solar infrared light regulating smart windows based on organic materials

“…Other devices used deformable polyurethane coated with gold to act as a modifiable reflector, termed a “butterfly‐wing‐like smart window” (Figure 5). [36] While these two devices rely on metals to do the actual reflection, organic equivalents could be substituted in the future; for example, the nickel could theoretically be replaced by ChLC flakes [75] or the polyurethane coated with a reflective layer of ChLCs or cellulose nanocrystals [76] . See Table 1 for a summary of all the devices discussed in this section.…”