Optically Tunable Chiral Plasmonic Guest–Host Cellulose Films Weaved with Long-range Ordered Silver Nanowires

Abstract

Plasmonic materials with large chiroptical activity at visible wavelength have attracted considerable attention due to their potential applications in metamaterials. Here we demonstrate a novel guest-host chiral nematic liquid crystal film composed of bulk self-co-assembly of the dispersed plasmonic silver nanowires (AgNWs) and cellulose nanocrystals (CNCs). The AgNWs-CNCs composite films show strong plasmonic optical activities, that are dependent on the chiral photonic properties of the CNCs host medium and orientation of the guest AgNWs. Tunable chiral distribution of the aligned anisotropic AgNWs with long-range order is obtained through the CNCs liquid crystal mediated realignment. The chiral plasmonic optical activity of the AgNWs-CNCs composite films can be tuned by changing the interparticle electrostatic repulsion between the CNCs nanorods and AgNWs. We also observe an electromagnetic energy transfer phenomena among the plasmonic bands of AgNWs, due to the modulation of the photonic band gap of the CNCs host matrix. This facile approach for fabricating chiral macrostructured plasmonic materials with optically tunable property is of interest for a variety of advanced optics applications.

Printing Flowers? Custom-Tailored Photonic Cellulose Films with Engineered Surface Topography

“…Cholesteric assembly of CNCs allows for control of chiral lightmatter interactions in photonic structure that is not only relevant for fundamental aspects but also for practical interests. [37][38][39] To highlight the wrinkle-induced iridescence, we chose CWF4 as an ideal example due to its cholesteric photonic band-gap was far away from the visible range. When a collimated white light beam impinged on the film surface and aligned with a surface wrinkle perpendicular to the plane of light incidence, it exhibited a striking rainbow-like appearance that derived from the grating-induced light interference ( Figure 4A).…”

Biomolecule‐Enabled Chiral Assembly of Plasmonic Nanostructures

“…They confirmed that the composite film had chiral nematic phase and Au NPs were incorporated in the host CNC matrix, through polarized optical microscopy (POM) and SEM analysis. In a further research by Ding et al., silver nanowires (Ag NWs) with a high aspect ratio, which had a weak liquid crystalline property by itself, were introduced to achieve coalignment of CNC nanorod and Ag NW in a chiral nematic phase . Ag NWs‐CNC composite film with a long‐range chiral ordering of the Ag NWs presented a strong plasmonic CD response in near ultraviolet and visible region.…”

Structural Transition in Liquid Crystal Bubbles Generated from Fluidic Nanocellulose Colloids

“…Low‐magnification scanning electron microscopy (SEM) images of the LCB hydrogel clearly demonstrated the preservation of spherical shape, a smooth surface at the bubble inner‐interface and a repeating lamellar‐like structure perpendicular to its surface (Figure b). In the chiral nematic‐ordered LCBs, the CNCs were retained in the lamellar bubble interface region with a twisting in a left‐handed direction,,, indicating that the bubble film was in a chiral nematic order, with the helical director perpendicular to the film surface (Figure c,d). However, in the case of nematic‐ordered LCBs, SEM analyses revealed that the rod‐like CNCs were highly aligned, with planar anchoring (Figure e).…”