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

• Published in: Particle & particle systems characterization 2020-05, Vol.37 (5), p.n/a
• Main Authors: Madhuri, Pappu Lakshmi, Shuddhodana, Judeh, Zaher M. A., Abdulhalim, Ibrahim
• Format: Article
• Language: English
• Subjects: Agglomeration; Biocompatibility; cochleates; Crystal structure; Drug delivery systems; Electric potential; Light scattering; Liquid crystals; Metamaterials; Nanoparticles; tunable metamaterials; Voltage
• ISSN: 0934-0866; 1521-4117
• DOI: 10.1002/ppsc.202000067

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. A tunable photonic metamaterial is demonstrated using hollow cochleate particles embedded in a liquid crystal (LC) matrix exhibiting controlled light scattering with voltage and temperature. The biocompatible cochleates are among many other nanoporous microparticles used for drug delivery, wherein a potential application is highlighted for tunable devices.