Structural Colors by Synergistic Birefringence and Surface Plasmon Resonance

Abstract

One-dimensional nanomaterials including cellulose nanocrystals (CNCs) and gold nanorods (GNRs) are widely used in optical materials due to their respective inherent features: birefringence with accompanying light retardation and surface plasmon resonance (SPR). Herein, we successfully combine these properties of both nanorods to generate synergistic and readily tunable structural colors in hybrid composite polymer films. CNCs and GNRs are embedded either in the same or in separate films after unidirectional alignment in dynamic hydrogels. By synergistically leveraging CNCs and GNRs with diverse amounts in hybrid films or stacked separate films, wide-ranging structural colors are obtained, far beyond those from films solely with aligned CNCs or GNRs. Higher GNR contents enhance light absorption at 520 nm with promoted magenta colors, while more CNCs affect the overall phase retardation with light absorption between 400 and 700 nm between crossed polarizers. Moreover, adjusting the angles between films solely with CNCs or GNRs via a stacking/rotating technique successively manipulates colors with flexible film combinations. By rotating the films with aligned GNRs (0–180°), light absorption can traverse from ∼500 to 650 nm. Thus, tuning the adjustable synergism of birefringence of CNCs and SPR of GNRs provides great potential for structural colors, which enlightens inspirations for designing functional optical materials.

Terahertz Birefringent Biomimetic Aerogels Based on Cellulose Nanofibers and Conductive Nanomaterials

“…The terahertz (THz) electromagnetic frequency regime is on the border between optics and electronics. − THz science and technology have advanced rapidly in the last years, attracting more and more attention in particular due to the need for higher frequencies of the high-speed sixth-generation (6G) communication. , This leads to an urgent requirement of high-performance THz devices or materials for this spectral region. The characterization in terms of optical properties, often anisotropic, is crucial for developing THz devices, such as phase shifters, polarizers, shields, and absorbers. − Therein, the most critical parameters are refractive index, absorption, and birefringence. − The birefringence is the difference between the refractive indices for different light propagation directions in an anisotropic medium. For developing THz optical devices, due to the longer wavelength, a larger phase shift compared to devices operating in the visible range is required.…”

Bioinspired Multi‐Stimuli Responsive Actuators with Synergistic Color‐ and Morphing‐Change Abilities

“…The spiral arrangement of the LC molecular layer will cause periodic changes in the optical refractive index, resulting in periodic birefringent extinction fringes in the fingerprint texture. [ 35–37 ] The spacing of the fringes is equal to half the pitch ( p /2). The wavelength λ of the selectively reflected light and the pitch p of the cholesteric LC material can be described by Bragg's reflection equation of crystal diffraction: …”

Trendbericht: Makromolekulare Chemie

“…Zhang und Kolleg:innen haben gezeigt, wie eine Synergie aus Doppelbrechung und Oberflächen-Plasmonenresonanz wirkt. 55) Durch selektive Anordnung und Orientierung von Goldnanostäbchen und Cellulose-Nanokristallen in Polymergelen oder -filmen erzeugten sie verschiedene Farben.…”