Cochleate‐Doped Liquid Crystal as Switchable Metamaterial Window Mediated by Molecular Orientation Modified Aggregation

Abstract

A diversity of fascinating hollow and porous micro and nanoparticles are being developed for drug delivery purposes; however, their applications in other systems are barely touched. When filled by an active material, they form a tunable photonic metamaterial. Here, a small concentration of organic hollow cylinders called cochleates embedded into liquid crystals (LCs) is demonstrated to form a new switchable composite to control light scattering with voltage and temperature. The biocompatible cochleates, which are hollow, tube‐like, and hydrophilic in nature, can trap the liquid crystal molecules thus altering the system behavior. A switching device as thin as 6 µm with 12 wt% cochleates concentration is shown to be adequate to reveal a switchable privacy window. Possible molecular arrangement of the liquid crystal within the cochleate particles is suggested, and unexpected increase of the scattering with temperature depending on the applied voltage is observed as a result of change in the cochleate aggregation depending on the LC molecule orientation.

Advanced liquid crystal-based switchable optical devices for light protection applications: principles and strategies

“…As shown in Fig. 13a , researchers used three types of nanoscale and microscale particles to demonstrate this concept: (1) cochleate particles 163 , (2) colloids of decanol 164 , and (3) nanoporous Si microparticles 165 . In the off and on states, the rise and fall times of these windows were approximately a few milliseconds and tens of milliseconds, respectively.…”

“…Scattering-based equipment causes radiation to be scattered in the forward direction 163 , 164 , 166 , and protection is not effective under strong sunlight. The light protection method of multi-mechanism integration combines traditional light energy transformation, reflected transfer, and scattering transfer, and it was widely applied in recent years.…”

“…The material had 86% transmittance in the transparent state and could switch to the scattering state within 10 to 100 ms, where the specular transmittance decreased to 11% 166 . Scattering-based equipment causes radiation to be scattered in the forward direction 163,164,166 , and protection is not effective strong sunlight. The light protection method of multi-mechanism integration combines traditional light energy transformation, reflected transfer, and scattering transfer, and it was widely applied in recent years.…”

Soft‐Matter‐Based Hybrid and Active Metamaterials

“…[ 64,137 ] Motivated by the great likelihood of implementing tunable ultracompact on‐chip devices, the development of LC‐based hybrid colloidal MMs has thus become a crucial research area over the last few years. [ 64,137,143,145–155 ] This section introduces and discusses LC‐based self‐assembling phenomena for active colloidal MMs, with particular emphasis on recent advances in the field. It then briefly considers a broad spectrum of properties and capabilities of self‐organized plasmonic hybrids loaded with LCs and provide examples of active MMs which interact with electromagnetic radiation in the visible and infra‐red regions.…”

Liquid, Transparent, and Antideformable Thermochromic Photonic Crystals for Displays

“…[ 1–7 ] Responsive photonic crystals (PCs) [ 8–15 ] that can mimic and show stimulus adjustable structural colors are fascinating. In particular, thermochromic photonic crystals (TPCs) [ 16 ] based on ordered packing of colloidal particles that can alter their optical properties in response to temperatures have attracted considerable attention due to their potential applications in temperature sensors, [ 17–24 ] smart widow, [ 25–28 ] biomonitors, [ 29–32 ] actuators, [ 31,33 ] displays, [ 34,35 ] lasers, [ 36 ] and printings. [ 37–39 ]…”